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Antibodies recognizing infliximab (IFX) may develop in a proportion of treated patients, leading to loss of response or hypersensitivity reactions (HRs). T cell response to IFX has been poorly investigated. This paper was addressed to detect IFX-specific T cells in treated patients with inflammatory diseases developing, or not, anti-drug antibodies (ADA) and to correlate the presence of specific T cells with the clinical outcomes of the treatment. A co-culture system of IFX-loaded dendritic cells and purified autologous CD4+ T cells was used to detect memory T cells in 32 ADA+ and 39 ADA- IFX-treated patients and control groups. The cytokine profile of IFX-specific T cells was also studied in culture supernatants. IFX-specific cell proliferation was detected mainly in cells from ADA+ patients, irrespective of their different diseases. HR patients displayed higher T cell proliferation than non-responder and tolerant patients. A mixed [interferon (IFN)-γ, interleukin (IL)-13, IL-10] cytokine profile was shown in cells from ADA+ patients, while IL-10 was the most frequently detected cytokine in the supernatants of cultures from ADA- patients. Immunoglobulin (Ig)E+ADA+ patients with previous HRs exhibited a more pronounced type 2 profile than IgE-ADA+ patients. This work provides evidence that IFX-specific circulating T cells are detectable mainly in ADA+ patients with HRs, regardless of their disease. The IFX-induced cytokine pattern partially correlates with the ADA isotype. [ABSTRACT FROM AUTHOR]

The mechanisms causing non-responsiveness to hepatitis B surface antigen (HBsAg) vaccines in man remain elusive. The increased incidence of non-responsiveness in subjects with HLA-DR3+ or -DR7+ haplotypes suggests that immune response mechanisms governed by genes of the MHC are involved. Homozygotes for these two haplotypes are found almost exclusively in the non-responder (NR) population. It is conceivable that antigen-presenting cells (APC) of NR are defective in the uptake of HBsAg and that they are unable to present this Ag adequately. Previously, we demonstrated thatDR2+,DR7+ andDP4+ NR were able to present HBsAg. In the present paper we demonstrate that six DR0301+ NR, five of which are homozygous for this marker, were able to take up, process and present HBsAg to HBsAg-specific, DR0301-restricted T cell lines. Non-fractionated peripheral blood mononuclear cells (PBMC) from the DR0301+ NR did not proliferate to HBsAgin vitro, whereas they proliferated vigorously upon stimulation with tetanus toxoid, thus ruling out the presence of a generalized immunodeficiency. We therefore conclude that HLA-DR0301+ NR vaccinees are not deficient in their HBsAg-presentation. Because it was demonstrated that recently activated T cells can apparently bypass the requirement for B7, we may have overlooked the role of the B7-co-stimulation in our set-up that used HBsAg-specific T cell lines. Therefore we examined the expression of B7 co-stimulatory molecules on NR-APC. CD86 was normally present on these cells and was not down-regulated after culturing the PBMC in the presence of HBsAg. We conclude that CD86 expression on CD14+ monocytes of DR0301- and DR07-homozygous poor responders is not deficient and cannot be the mechanism underlying the non-responsiveness of these subjects. [ABSTRACT FROM AUTHOR]

Immunosurveillance requires the migration of lymphocytes and their activation to induce proliferation and effector function. Effective immunity requires an optimal supply of nutrients to lymphocytes. Cells contain nutrient sensing apparatus such as adenosine 5′-monophosphate-activated protein kinase (AMPK) that surveys intracellular ATP levels. Immunity declines during ageing and one possibility is that the energy balance may be altered in old lymphocytes. This paper summarizes recent data identifying a convergence of senescence and nutrient signalling pathways in lymphocytes that inhibit both T cell and natural killer (NK) cell function during ageing. Significantly, these pathways can be inhibited to enhance the activity of these cells. [ABSTRACT FROM AUTHOR]

The article reports on the effects of the physical state of the antigen and of lymphoreticular cell proliferation on the response to intraperitoneal injection of bovine serum albumin in rabbits. A study was conducted to determine whether the time relationships of Corynebacterium parvum administration and antigen injection are important in particular to show whether it would produce same adjuvant effects as Corynebacterium parvum injected 6 days prior to the injection of the antigen. The result of the study reveals that higher affinity antibody especially if the quantity of antigen available causes specific lymphoid proliferation.

Summary: Capping protein regulator and myosin 1 linker 2 (CARMIL2) deficiency is characterized by impaired T cell activation, which is attributed to defective CD28‐mediated co‐signaling. Herein, we aimed to analyze the effect of exogenous interleukin (IL)‐2 on in‐vitro T cell activation and proliferation in a family with CARMIL2 deficiency. This study included four children (one male and three females; aged 2·5–10 years at presentation). The patients presented with inflammatory bowel disease and recurrent viral infections. Genetic analysis revealed a novel homozygous 25‐base pairs deletion in CARMIL2. Immunoblotting demonstrated the absence of CARMIL2 protein in all four patients and confirmed the diagnosis of CARMIL2 deficiency. T cells were activated in‐vitro with the addition of IL‐2 in different concentrations. CD25 and interferon (IFN)‐γ levels were measured after 48 h and 5 days of activation. CD25 surface expression on activated CD8+ and CD4+ T cells was significantly diminished in all patients compared to healthy controls. Additionally, CD8+ T cells from all patients demonstrated significantly reduced IFN‐γ production. When cells derived from CARMIL2‐deficient patients were treated with IL‐2, CD25 and IFN‐γ production increased in a dose‐dependent manner. T cell proliferation, as measured by Cell Trace Violet, was impaired in one patient and it was also rescued with IL‐2. In conclusion, we found that IL‐2 rescued T cell activation and proliferation in CARMIL2‐deficient patients. Thus, IL‐2 should be further studied as a potential therapeutic modality for these patients. [ABSTRACT FROM AUTHOR]

Adoptive T cell therapy of cancer employs a large number of ex-vivo-propagated T cells which recognize their targets either by virtue of their endogenous T cell receptor (TCR) or via genetic reprogramming. However, both cell-extrinsic and intrinsic mechanisms often diminish the in-vivo potency of these therapeutic T cells, limiting their clinical efficacy and broader use. Direct activation of human T cells by Toll-like receptor (TLR) ligands induces T cell survival and proliferation, boosts the production of proinflammatory cytokines and augments resistance to regulatory T cell (Treg) suppression. Removal of the TLR ligand-binding region results in constitutive signalling triggered by the remaining cytosolic Toll/interleukin-1 receptor (TIR) domain. The use of such TIR domains therefore offers an ideal means for equipping anti-tumour T cells with the arsenal of functional attributes required for improving current clinical protocols. Here we show that constitutively active (ca)TLR-4 can be expressed efficiently in human T cells using mRNA electroporation. The mere expression of caTLR-4 mRNA in polyclonal CD8 and CD4 T cells induced the production of interferon (IFN)-γ, triggered the surface expression of CD25, CD69 and 4-1BB and up-regulated a panel of cytokines and chemokines. In tumour-infiltrating lymphocytes prepared from melanoma patients, caTLR-4 induced robust IFN-γ secretion in all samples tested. Furthermore, caTLR-4 enhanced the anti-melanoma cytolytic activity of tumour-infiltrating lymphocytes and augmented the secretion of IFN-γ, tumour necrosis factor (TNF)-α and granulocyte-macrophage colony-stimulating factor (GM-CSF) for at least 4 days post-transfection. Our results demonstrate that caTLR-4 is capable of exerting multiple T cell-enhancing effects and can potentially be used as a genetic adjuvant in adoptive cell therapy. [ABSTRACT FROM AUTHOR]

Regulatory T cells (Tregs) have potential applications in clinical disease therapy, such as autoimmune diseases and transplant rejection. However, their numbers are limited. Forkhead box protein 3 (FoxP3) is a key transcription factor that controls Treg development and function. Here, we generated a cell-permeable fusion protein, protein transduction domain (PTD)-conjugated mouse FoxP3 protein (PTD-mFoxP3), and evaluated whether PTD-mFoxp3 can alleviate rheumatoid arthritis (RA) in the collagen-induced arthritis (CIA) mouse model. As expected, PTD-mFoxP3 was transduced into cells effectively, and inhibited T cell activation and attenuated the cell proliferation. It decreased interleukin (IL) 2 and interferon (IFN)-γ expression, and increased IL-10 expression in activated CD4+CD25− T cells. PTD-mFoxP3-transduced CD4+CD25− T cells attenuated proliferation of activated CD4+CD25− T cells. In addition, PTD-mFoxP3 blocked the Th17 differentiation programme in vitro and down-regulated IL-17 production from T cells by modulating induction and levels of retinoid-related orphan receptor gamma t (RORγt). Intra-articular delivery of PTD-mFoxP3 delayed disease incidence remarkably and alleviated autoimmune symptoms of CIA mice. Moreover, protective effects of PTD-mFoxP3 were associated with regulating the balance of T helper type 17 (Th17) and Tregs. These results suggest that PTD-mFoxP3 may be a candidate for RA therapy. [ABSTRACT FROM AUTHOR]

Renal tubular epithelial cells ( TECs) are one of the main targets of alloreactive T cells during acute rejection. We hypothesize that TECs modulate the outcome of alloimmunity by executing immunosuppressive effects in order to dampen the local inflammation. We studied whether TECs possess immunosuppressive capacities and if indoleamine 2,3-dioxygenase ( IDO) might play a role in suppressing T cell alloreactivity. Next, we studied the role of programmed death ligand 1 ( PD- L1) and intercellular adhesion molecule-1 ( ICAM-1 with regard to TEC-related immunomodulatory effects. CD3/ CD28 and alloactivated peripheral blood mononuclear cells were co-cultured with activated TECs. We analysed CD4+ and CD8+ T cell proliferation and apoptosis in the absence or presence of IDO inhibitor 1-methyl- L-tryptophan (1- L- MT), anti- PD- L1 and anti- ICAM-1. Further, we examined whether inhibition of T cell proliferation was cell-cell contact-dependent. We found that TECs dose-dependently inhibited CD4+ and CD8+ T cell proliferation ( P < 0·05). Activated TECs showed significantly increased IDO activity and up-regulated PD- L1 and ICAM-1 expression. Suppressed CD4+ and CD8+ T cell proliferation was only partially restored or failed to restore using 1- L- MT. Activated TECs increased early and late apoptosis of proliferating CD4+ and CD8+ T cells; only CD4+ T cell apoptosis was statistically affected by 1- L- MT. Transwell experiments revealed that TEC-mediated immunosuppression is cell-cell contact-dependent. We found that anti- ICAM-1 affected only CD4+ T cell apoptosis and not T cell proliferation. Our data show that TECs suppress both CD4+ and CD8+ T cell proliferation contact dependently. Interestingly, inhibition of proliferation and enhancement of apoptosis of T cell subsets is differentially regulated by indoleamine 2,3-dioxygenase and ICAM-1, with no evidence for the involvement of PD- L1 in our system. [ABSTRACT FROM AUTHOR]

Activated CD4+ T cells undergo blastogenesis and proliferation and they express several surface receptors, including β2-microglobulin-free human leucocyte antigen ( HLA) heavy chains (open conformers). Intravenous immunoglobulin (IVIg) suppresses activated T cells, but the mechanism is unclear. IVIg reacts with HLA- Ia/ Ib antigens but its reactivity is lost when the anti- HLA- E Ab is adsorbed out. Anti- HLA- E antibodies may bind to the peptides shared by HLA- E and the HLA- I alleles. These shared peptides are cryptic in intact HLA, but exposed in open conformers. The hypothesis that anti- HLA- E monoclonal antibodies ( mAbs) that mimic HLA- I reactivity of IVIg may suppress activated T cells by binding to the shared peptides of the open conformers on the T cell surface was tested by examining the relative binding affinity of those mAbs for open conformers coated on regular beads and for intact HLA coated on iBeads, and by comparing the effects on the suppression of phytohaemagglutinin ( PHA)-activated T cells of three entities: IVIg, anti- HLA- E mAbs that mimic IVIg [Terasaki Foundation Laboratory (TFL)-006 and (TFL)-007]; and anti- HLA- E antibodies that do not mimic IVIg ( TFL-033 and TFL-037). Suppression of blastogenesis and proliferation of those T cells by both IVIg and the anti- HLA- E mAbs was dose-dependent, the dose required with mAbs 50-150-fold lower than with IVIg. TFL-006 and TFL-007 significantly suppressed blastogenesis and proliferation of activated CD4+ T cells, but neither the non- IVIg-mimicking mAbs nor control antibodies did so. The suppression may be mediated by Fab-binding of TFL-006/ TFL-007 to the exposed shared peptides. The mAb binding to the open conformer may signal T cell deactivation because the open conformers have an elongated cytoplasmic tail with phosphorylation sites (tryosine320/serine335). [ABSTRACT FROM AUTHOR]

Protein kinases mediate protein phosphorylation, which is a fundamental component of cell signalling, with crucial roles in most signal transduction cascades: from controlling cell growth and proliferation to the initiation and regulation of immunological responses. Aberrant kinase activity is implicated in an increasing number of diseases, with more than 400 human diseases now linked either directly or indirectly to protein kinases. Protein kinases are therefore regarded as highly important drug targets, and are the subject of intensive research activity. The success of small molecule kinase inhibitors in the treatment of cancer, coupled with a greater understanding of inflammatory signalling cascades, has led to kinase inhibitors taking centre stage in the pursuit for new anti-inflammatory agents for the treatment of immune-mediated diseases. Herein we discuss the main classes of kinase inhibitors; namely Janus kinase ( JAK), mitogen-activated protein kinase ( MAPK) and spleen tyrosine kinase ( Syk) inhibitors. We provide a mechanistic insight into how these inhibitors interfere with kinase signalling pathways and discuss the clinical successes and failures in the implementation of kinase-directed therapeutics in the context of inflammatory and autoimmune disorders. [ABSTRACT FROM AUTHOR]

Systemic sclerosis ( SSc) is a chronic disease, with early activation of the immune system. The aim of our work was to address how SSc-mesenchymal stem cells ( MSCs), although senescent, might preserve specific immunomodulatory abilities during SSc. MSCs were obtained from 10 SSc patients and 10 healthy controls ( HC). Senescence was evaluated by assessing cell cycle, β-galactosidase (β- Gal) activity, p21 and p53 expression; doxorubicin was used as acute senescence stimulus to evaluate their ability to react in stressed conditions. Immunomodulatory abilities were studied co-culturing MSCs with peripheral blood mononuclear cells ( PBMCs) and CD4+ cells, in order to establish both their ability to block proliferation in mixed lymphocyte reaction and in regulatory T cells ( Tregs) induction. SSc- MSC showed an increase of senescence biomarkers. Eighty per cent of MSCs were in G0- G1 phase, without significant differences between SSc and HC. SSc- MSCs showed an increased positive β- Gal staining and higher p21 transcript level compared to HC cells. After doxorubicin, β- Gal staining increased significantly in SSc- MSCs. On the contrary, doxorubicin abolished p21 activation and elicited p53 induction both in SSc- and HC- MSCs. Interleukin ( IL)-6 and transforming growth factor ( TGF)-β-related transcripts and their protein levels were significantly higher in SSc- MSCs. The latter maintained their immunosuppressive effect on lymphocyte proliferation and induced a functionally regulatory phenotype on T cells, increasing surface expression of CD69 and restoring the regulatory function which is impaired in SSc. Increased activation of the IL-6 pathway observed in our cells might represent an adaptive mechanism to senescence, but preserving some specific cellular functions, including immunosuppression. [ABSTRACT FROM AUTHOR]

The effects of dexamethasone phosphate and interleukin-7 upon the proliferation of T-cells and the production of interferon-γ in the newborn's cord blood mononuclear cell cultures were studied. The capability of dexamethasone to enhance T-cell proliferation induced by anti-CD3 with interleukin-7 in some newborn cord blood mononuclear cell cultures was identified. Dexamethasone suppressed production of interferon-γ in 68-h cell cultures stimulated with anti-CD3 both in the presence of interleukin-7 and without it. However, a 68-h cultivation of newborn blood cells with dexamethasone, anti-CD3 and interleukin-7 resulted in the accumulation of T-lymphocytes capable of producing interferon-γ after restimulation. As a result of it the amount of interferon-γ producing CD7+ T-cells and the concentration of interferon-γ in cultural supernatants were maximal in the cell cultures incubated with anti-CD3, interleukin-7 and dexamethasone during the first 68 h and subsequently restimulated with phorbol 12-myristate 13-acetate and ionomycin. The stimulation of neonatal or adult blood cells by dexamethasone, anti-CD3 and interleukine-7 also causes a decrease in the number of naïve T-cells and central memory cells and an increase in the number of effector memory CD7+CD45RA+CD62L– cells in cultures. It is possible that these effects are caused by the influence of dexamethasone on IL-7 receptor expression: it is known that IL-7 receptor alpha-chain gene is a glucocorticoid-inducible gene. [ABSTRACT FROM AUTHOR]

B cells that make polyreactive antibodies (PAB+ cells) express polyreactive Ig receptors on their surface and call bind a variety of different antigens. The present study shows that PAB+ cells are widely distributed, are present in varying numbers in different lymphoid organs and that their phenotype varies depending on the organs from which they are isolated. Up to 10 times more cells ill PAB+ enriched populations bind antigens as compared to PAB- populations. Comparison of PAB+ with B-1+ cells showed that a high percentage of PAB+ cells are B-1+, but that many PAB+ cells do not express B I cell surface markers and, in fact, are B-1-. It is concluded that the B cell population consists of PAB+/B-1+, PAB+/B-1-, PAB-/B-1+, and PAB-/B-1- cells. The presence of PAB+ cells in the thymus points to the possibility that PAB+ cells may carry endogenous host antigens from peripheral tissues to the thymus where they may contribute to immunological tolerance. [ABSTRACT FROM AUTHOR]

The current study was designed to test the ability of recombinant Vaccinia virus rVV) encoding essential components of an artificial antigen-presenting cell to activate antigen-specific T cells in vitro. We have constructed a set of rVV encoding separately or in combination a CD4+ T cell-specific epitope (the 133-145 peptide of chicken conalbumin), the MHC class II molecule I-Ak, and costimulatory molecules (mB7-l and mB7-2). Cultured cells infected with rVV encoding both the antigen and the presenting MHC, hut not either one alone, could activate cloned CD4+ T cells specific for the virus-encoded epitope. Additional co-expression of mB7-1 and mB7-2 resulted in further enhancement of T cell response. Thus, our rVV vector expressing four different foreign gene products elicited the highest proliferation rates of antigen-specific cloned T cells. [ABSTRACT FROM AUTHOR]

Integral membrane proteins (IMP) represent a serologically distinct class of mycobacterial antigens which are potent stimulators of human T cells (Mehrotra et al., Clin Exp Immunol 1995; 102:626). The range of IMP from Mycobacterium fortuitum was resolved by continuous elution SDS-PAGE to recover 31 discrete fractions covering bands up to &ap; 58 kD. The fractions, after removal of SDS. were subjected to human T cell proliferation assays for the identification of immunodominant molecule(s). A low molecular weight (<20kD) fraction was able to stimulate T cells from 11 out of 12 donors comprising mainly tuberculoid leprosy patients. The described protocol is well suited to situations where large quantities of antigenic protein mixtures must be processed in order to get the purified molecules/fractions in amounts required for immunoepidemiological studies. [ABSTRACT FROM AUTHOR]

Several T cell defects have been described in the antibody deficiency disease, CVID, but there have been few data on the generation of responses of specific T cell populations to primary neoantigens. We have now used immunization with the neoantigens, keyhole limpet haemocyanin (KLH) and DNP-Ficoll, to evaluate immune responses in CVID patients and normal donors. B and T cell responses were examined 2 and 4 weeks post-immunization. Sera were examined for IgM and IgG anti-KLH responses by ELISA and for anti-DLP-Ficoll activity by haemagglutination. The frequency of KLH-responsive T cells was measured by DNA synthesis in a limiting dilution culture system. Low density cells enriched for dendritic cells were pulsed with KLH and cultured with different numbers of autologous T cells. T cells from normal donors and from patients showed a low frequency of antigen-specific precursor T cells (≤1:200 000). After KLH immunization the frequency increased in normal donors (1:60 000 and 1:30 000 at 2 and 4 weeks, respectively), while in CVID patients it did not change from the preimmunization level. The defect may extend to a dysfunction of antigen-specific cells, rather than being solely due to the reduced numbers of cells, since mean responses of 'positive' wells were also reduced. The serum-specific antibody response paralleled the T cell data, in that all normal donors but none of the CVID patients generated IgG KLH-specific antibodies. CVID patients did produce IgM antibodies against the T-independent DNP-Ficoll, but at a lower level than normal controls. These data show that both T and B cells from CVID patients have defective responses to specific antigen, implicating both lineages in the antibody deficiency. [ABSTRACT FROM AUTHOR]

We looked for autoantibodies to Cl inhibitor (Cl-INH) and evaluated the relationship of their presence to the associated lymphoproliferative diseases and to the cleaved form of Cl-INH in 13 patients with acquired Cl-INH deficiency (acquired angio-oedema (AAE)). At the lime of manifestation of angio-oedema symptoms or within a few years the following diseases were diagnosed: liver angioma (n = 1), M-components(n = 7, one of whom also had echinococcal liver cysts), breast cancer (n = 1), chronic lymphocytic leukaemia (CLL;n = 1); three patients had no associated disease. Anti-Cl-INH autoantibodies, measured both as immunoglobulin binding to Cl-INH immobilized onto microtitre plates (ELISA) and as plasma inhibitory activity of Cl-INH function, were found in 12 patients. Binding of Cl-INH to paraproteins, transferred to Immobilon after agarose gel electrophoresis, was delectable in five of seven M-components associated with AAE. Immunoblotting analysis of SDS PAGE-separated plasma demonstrated that Cl-INH circulated in the cleaved 96-kD form in the 12 patients with autoantibodies, but not in the one without. In conclusion, the large majority of our patients have autoantibodies to Cl-INH, Circulating autoantibodies are necessary for the generation of cleaved Cl-INH. The paraproteins associated with AAE are frequently autoantibodies to Cl-INH and thus account for its consumption. [ABSTRACT FROM AUTHOR]

Chloroquine (Chl) is an anti-rheumatic drug that is widely used in the treatment of rheumatoid arthritis (RA). It seems that T cells are important in the pathogenesis of RA, but it is not known whether Chl acts via inhibition of T cell function. We here present evidence that Chl, just like cyclosporine A (CsA), inhibits T cell proliferation as induced with immobilized αCD3 MoAb in a concentration-dependent manner, at least partly through interfering with the production of IL-2 protein and the induction of IL-2 mRNA. Furthermore, Chl impedes the responsiveness of T cell clones to IL-2 since (1) the inhibition of αCD3 MoAb-induced proliferation by Chl could not be reversed by rIL-2 and (2) Chl directly blocks IL-2-driven proliferation of cloned T cells. Chl appeared to interfere with the internalization (50% inhibition) and degradation (total blockade) of rIL-2. Finally, the combination of Chl and CsA synergistically inhibited T cell proliferation. We conclude that Chl may inhibit functional properties of human T cells, although the drug is 100- to 1000-fold less potent than CsA in inhibiting T cell proliferation and IL-2 production, respectively. It is speculated that the in vitro effects of Chl might be relevant in explaining the anti-rheumatic effect of this drug in patients with RA. [ABSTRACT FROM AUTHOR]

The influence of ageing on phenotype and function of CD4+ T cells was studied by comparing young (19-28 years of age) and aged (75-84 years of age) donors that were selected using the SENIEUR protocol to exclude underlying disease. An age-related increase was observed in the relative number of memory ceils, not only on the basis of a decreased CD45RA and increased CD45RO expression, but also on the basis of a decrease in the fraction of CD27+CD4+ T cells. Our observation that the absolute number of CD45RO+CD4+ T cells was increased, while absolute numbers of CD27- CD4- T cells remained unchanged in aged donors, indicates that the latter subset does not merely reflect the size of the CD45RO+ CD4+ T cell pool. The increased fraction of memory cells in the aged was functionally reflected in an increased IL-4 production and T cell proliferation, when cells were activated with the combination of anti-CD2 and anti-CD28, whereas IL-2 production was comparable between both groups. No differences were observed with respect to proliferative T cell responses or IL-2 production using plate-bound anti-CD3 or phytohaemagglutinin (PHA). The observation that IL-4 production correlated with the fraction of memory cells in young donors but not in aged donors suggests different functional characteristics of this subset in aged donors. [ABSTRACT FROM AUTHOR]

Successful T cell activation via the T cell receptor (TCR)/CD3 complex requires at least one contact- dependent second signal delivered by costimulatory molecules, including the B7/BB I molecule, that are present on antigen-presenting cells (APC). SLE is characterized by multiple complex lymphocyte abnormalities of undefined molecular origin. It is currently unclear whether an intrinsic defect of T cell or an underlying APC dysfunction is responsible for defective in vitro proliferation of T cells from patients with SLE. We planned the present experiments to ask whether the TCR/CD3-mediated and B7/BBI-costimulated T cell proliferation is normal in these patients. We used enriched T cell populations that were stimulated with an anti-CD3 MoAb in the presence of controlled quantities of functional B7/BBI antigen. Freshly isolated T cells from 17 SLE patients (10 and seven patients with either active or inactive disease, respectively) and 11 normal individuals were cocultured with irradiated B7/BB 1 -transfected P815 cells or parental P815 cells in the presence of OKT3 MoAb at optimal and suboptimal concentrations for 25-7 days. Normal or SLE T cells responded similarly to stimulation via anti-CD3, in the absence of B7/BB 1 antigen. A several-fold increase in T cell proliferation in the presence of B7/BB1 antigen was observed. Proliferation was inhibited in the presence of anti-B7/BB 1 MoAb, but not with control MoAbs. Interestingly, dose-response curves and time kinetics of 137/BB1 costimulation were similar in T cells from patients with either active or inactive SLE at the time of study, and normal individuals. In addition, no differences in the IL-2 receptor release by T cells cultured under these conditions were observed between SLE patients and normal individuals. These results demonstrate that CD28 signalling is not intrinsically impaired in patients with SLE; further studies to investigate whether abnormal B7/BB I expression is involved in the autoimmune process are needed. [ABSTRACT FROM AUTHOR]

Macrophage production of PDGF-B is believed to be important in the pathogenesis of diseases where chronic lung inflammation develops into fibrosis. Since tuberculosis is characterized by chronic inflammation and tissue fibrosis, we asked if lymphokines from lymphocytes stimulated by the Mycobacterium tuberculosis antigen PPD, contained factors capable of increasing human alveolar macrophage PDGF-B mRNA, Supernatants from both phytohaemagglutinin (PHA)- and purified protein derivative (PPD)-stimulated lymphocytes. when added to macrophages, induced an increase in the mRNA of PDGF-B, but not transforming growth factor-beta (TGF-β). When lymphocytes from contacts of patients with tuberculosis, patients with tuberculosis, and normal subjects were compared following PPD stimulation, the lymphocytes from the contacts had the greatest proliferation response, the greatest production of interferon-gamma (IFN-γ). and their lymphokines induced the greatest increase in PDGF-B mRNA in macrophages, Recombinant human IF-N-v reproduced this ability of lymphokines to increase macrophage PDGF-B mRNA. Finally, the increase in macrophage PDGF-B mRNA following incubation with supernatants from PPD stimulated lymphocytes was shown lo be due to IFN-γ, when the increase in macrophage PDGF-B mRNA was prevented by addition of anti-human IFN-γ antibody to the lymphocyte supernatant. This study indicated that antigen-stimulated lymphocytes released IFN-γ, which in turn resulted in an increase in PDGF-B mRNA in alveolar macrophages. Such a mechanism provides a link between the DTH response and the first stages of a fibrotic reaction, and may offer an explanation for the progression of chronic inflammation to fibrosis, as occurs in the lungs of patients with untreated pulmonary tuberculosis. [ABSTRACT FROM AUTHOR]

Molecular size and charge distribution of IgA of sera and glomerular eluates were investigated in ddY mice, spontaneously developing mesangial proliferativc glomerulonephritis (GN) with IgA deposition after 40 weeks of age. Scrum IgA levels were increased in aged ddY t-nice more than 40 weeks old with a significant increase (P<0.01) at the age of 60 weeks, comparing with those of BALB/c mice. The isoelectric focusing (IEF)spectrotype of pooled serum IgA in 60-week-old mice ranged from 4-2 to 5-5, being similar to those in younger ddY (16 weeks old) and control BALB/c mice (12 weeks old) without enhanced expression of specific IgA peaks. However, IgA in the glomerular eluates from the 60-week-old mice showed limited anionic spectrotypes from pH 4 2 to 4-8. HPLC of IgA in pooled sera and glomerular eluates of 16-, 40- and 60-week-old ddY mice, revealed markedly increased ratios of the dimeric IgA (dlgA) and polymeric IgA (pIgA) in the total IgA with age. In the contrast to serum profiles, monomeric IgA (mIgA) was always detected as the smallest peak of the IgA fractions in glomerular eluates. Furthermore, aged mice with severe GN showed a higher percentage of dlgA and pIgA in total IgA (80%) in the sera than that of the mice with mild GN (64%), HPLC analysis under acid condition of glomerular IgA from 40-week-old ddY mice showed a similar pattern of dIgA and plgA peaks in neutral buffer without the appearance of mIgA, These findings suggest that there is a selective mechanism for glomerular accumulation of more acid IgA among the polyclonally expanded IgA in old ddY mice, and that the polymeric form of IgA plays a pathogenic role in the development of mesangial proliferative GN in these mice. [ABSTRACT FROM AUTHOR]

The IL-2/IL-2 receptor (IL-2R) system has been investigated in 64 patients with multiple myeloma (MM), 31 with monoclonal gammopathies of undetermined significance (MGUS) and 20 normal controls. The MM data were related to clinical status by comparing active disease, i.e. at diagnosis and at relapse, and stable disease, i.e. complete remission and off-treatment plateau phase. Serum and urinary values of the soluble IL-2R (sIL-2R) were significantly increased in MM patients compared with normal controls and this increase was related to activity. MM patients with active disease gave significantly higher values than those with stable disease. Compared with normal controls, enriched B cell (but not T cell) preparations from peripheral blood mononuclear cells (PBMC) showed significantly increased proportions of IL-2R+ cells in MM and MGUS. However, the highest proportions were detected in active MM compared with stable MM and MGUS, Also, 16% of all MM patients, as opposed to 9%, of MGUS, had well-defined bone marrow IL-2R+ plasma cell populations. The lowest serum IL-2 values were found in active MM. Serial follow up of serum sIL-2R suggested that this peptide can be used as an additional marker of active malignancy. The data indicate that a disturbance of IL-2/IL-2R system is most pronounced in active MM. These findings may provide clues as to the T cell abnormalities in MM. [ABSTRACT FROM AUTHOR]

In order to evaluate the impact of induction and increase target antigen expression on immunotoxin potency, we measured the potentiating effect of recombinant immune interferon-gamma (rIFN-γ) on the cytotoxicity of an anti HLA-DR ricin A-chain immunotoxin (2G5 RTA-IT) on the myeloid cell line ML-3. After 48 h of incubation with rIFN-γ (500 U/ml) the percentage of 2G5-positive cells increased from 40% to 79%, and the 2G5 mean density was enhanced by 10-fold (11 000 versus 110 000 molecules/cell). Concurrently, rIFN-γ pretreatment induced a dramatic improvement of 2G5 RTA-IT dose effect eytotoxicity, as well as immunotoxin cytotoxicity kinetics. When 2G5 RTA-IT was used al the optimal dose of 10-8 M the maximum dose which avoided non-specific ricin A-chain cytotoxicity), the immunotoxin-induced cell kill increased with the percentage of DR-positive ML-3 cells according to a similar linear logarithmic function of rIFN-γ concentration. Moreover, in the same range of rIFN-γ concentrations, the killing values and the percentage of DR-positive ML-3 cells were similar if not identical. These findings imply that the enhancement of 2G5 RTA-IT cytotoxicity by rIFN-γ is mainly related to the rIFN-γ 2G5 antigen induction on HLA-DR negative cells when immunotoxin was used at 10-8 M. Furthermore. 2G5 RTA-IT dose effect cytotoxicity on DR-expressing ML-3 cells, when used at lower concentrations, was also increased by rIFN-γ in a dose dependent manner. This result suggests that for immunotoxin concentrations close lo the limiting membrane saturation dose (10-10 M), rIFN-γ may not solely act by inducing HLA-DR expression on DR-negative ML-3 subpopulation but also by increasing individual cellular DR density on DR expressing ML-3 cells. Finally, our study showed that immunotoxin potency on malignant cell populations which display an heterogeneous antigen expression, could be greatly improved by the use of rIFN-γ. [ABSTRACT FROM AUTHOR]

T cell reactivity to the 70 and 65 kD (p70 and p65) protein antigens derived from Mycobacterium bovis BCG strain was studied by measuring the proliferative responses of peripheral blood mononuclear cells from members of an isolated Aboriginal community resident in the Torres Straits islands. In the nine index leprosy cases the pattern of responsiveness to the purified antigens paralleled that to whole sonicates from M. leprae and BCG. In the 40 contacts of the index cases, a high correlation was observed between the responses to p70 and p65 as well as to the crude sonicates. Significant T cell responses to the purified antigens. as well as the crude sonicates, were obtained with cells from the majority of contacts. Limiting dilution analysis of precursor frequencies in the contacts confirmed the immunogenicity of the purified antigens and excluded both a mitogenic component and the presence of suppressor cells in those moderate or low responders whose blood contained sufficient precursors to be tested. p70 appeared to be more potent in stimulating a proliferative response than p65 at equivalent protein concentrations. No correlation between responder status to either antigen and disease type was detected in families. These findings provide confirmation of the importance of p70 and p65 as major T cell immunogens in man and indicate that they are both potential candidates for inclusion in a bivalent vaccine for leprosy and tuberculosis. [ABSTRACT FROM AUTHOR]

Though complement activation is recognized as a central event in inflammation in the rheumatoid joint, little attention has been paid to the role of the cytolytic membrane attack complex of complement in the pathogenesis of this disease. The membrane attack complex causes a variety of non-lethal effects in nucleated cells, including stimulation of release of inflammatory mediators, and cell proliferation. Thus in the rheumatoid synovium, non-lethal effects of complement membrane attack may play a major role in disease pathology. In order to investigate this possibility, assays for the detection of terminal complement complexes in biological fluids have been established, and used to demonstrate membrane attack pathway activation in rheumatoid arthritis. Terminal complement complexes were present in increased levels in synovial fluid (mean, 1,334 ng/ml) and plasma (mean, 513 ng/ml) in 20 patients with rheumatoid arthritis when compared with controls (mean, 285 ng/ml and 129 ng/ml respectively). Using an assay specific for the SC5b-9 complex it was demonstrated that the raised levels of terminal complement complexes in rheumatoid synovial fluid consisted of a mixture of inactive SC5b-9 complexes and fluid-phase complement membrane attack complexes. [ABSTRACT FROM AUTHOR]

T cell-derived helper factors can cause activated B cells to proliferate and differentiate into immunoglobulin (Ig)-secreting cells. In the pokeweed mitogen (PWM)-driven Ig production system, the cell-cell interaction necessary for the production of the helper factors was analysed. T cells were pulsed with PWM with or without autologous monocytes. The T cells were then isolated, and incubated for 48 h. Supernatants were tested for their ability to promote differentiation of activated B cells. We found that cell-cell contact between T cells and monocytes for the first 3 h of culture is required to produce the T cell-derived helper factors upon stimulation with PWM. We next examined which T cell subsets are involved in the production of helper factors and which surface molecules either on T cells or on monocytes are responsible for the cell-cell interaction to produce helper factors. A series of monoclonal antibodies were added to T cell subsets with monocytes during the PWM-pulsed period. Although T4+ and T8+ cells could produce almost equal amounts of helper factor activity upon PWM-stimulation, the interactions between T3 and T4 antigens on T4+ cells and Ia-like antigens on monocytes and those between T3 and T8 antigens on T8+ cells and HLA class I antigens on monocytes are respectively essential for the production of T4+ cell-derived and T8+ cell derived helper factors. [ABSTRACT FROM AUTHOR]

A commercially available polyspecific, monomeric IgG preparation suitable for intravenous administration (IgSRK; Sandoglobulin) can inhibit pokeweed mitogen (PWM)-induced proliferation of peripheral blood mononuclear cells (PBMC) by a small, but statistically significant, amount compared to control cultures. Such inhibition could not be demonstrated when PBMC were stimulated with the T cell mitogen phytohaemagglutinin. Surface phenotype analysis of the PWM-stimulated cells indicated that in IgSRK-containing cultures, the proportion of B cells was decreased and the proportion of T cells was increased compared to control cultures. This alteration in T:B ratio was not due to antigenic modulation of B or T cell markers from their surfaces. In addition, IgSRK inhibited the proliferation of T cell-depleted PBMC cultures stimulated by B cell proliferation factors (BCPF) but not by fixed protein A-bearing Staphyococcus aureus strain Cowan I. The capacity to inhibit B cell proliferation was independent of and distinct from its capacity to inhibit B cell differentiation, since IgSRK inhibited the differentiation of a B cell differentiation factor (BCDF)-sensitive line by BCDF (which contains no BCPF activity). IgSRK inhibited PWM-induced generation of cytoplasmic Ig+cells but had no effect on Ig secretion from mature Ig-secreting cells. Taken together, these findings suggest that IgSRK (which contains the IgG fraction from pooled plasma from 2,000 healthy donors) can inhibit T cell-dependent or T cell factor-dependent B cell proliferation and B cell differentiation. [ABSTRACT FROM AUTHOR]

Fractionation of human peripheral blood leucocytes (PBL) B cells by differential sedimentation on a discontinuous Percoll gradient separates B cell subpopulations which vary markedly in rates of spontaneous IgE synthesis, often revealing the presence of active IgE secreting cells which are totally suppressed within unfractionated PBL B cell preparations. The production in vitro of IgE by separated B cell populations from the same individual may respond disparately to an identical population of autologous T cells and to pokeweed mitogen. Kinetic studies revealed major differences in both the rates of release of cell-associated IgE between these B cell populations, and their rates of de novo IgE synthesis. From a methodological viewpoint, the use of this B ceil fractionation technique is demonstrated to improve greatly the efficiency of detection of T cell responsive IgE producing B cells in peripheral blood from atopics, and from a mechanistic standpoint raises the possibility that B cell heterogeneity may modulate the functional expression of IgE-regulatory T cells signals. [ABSTRACT FROM AUTHOR]

PHA activated human peripheral blood mononuclear cells (MNC) were incubated with human interleukin 2 (IL-2) in the absence or in the presence of 10-6-10-9 M hydrocortisone (HC). HC suppressed the proliferative response of the activated MNC to highly purified human leucocyte IL-2 in a dose dependent manner. This suppression was in full accordance with an inhibition of the IL-2 binding capacity, whereby the high affinity binding sites were reduced by 85%, while the low affinity sites were less affected. The mechanism by which HC inhibits the binding of IL-2 is still unknown. Evidence is presented that HC binds only weakly to IL-2. We conclude that HC interferes with the IL- 2 binding by modulating the binding and/or signal processing function of the IL-2 receptor. [ABSTRACT FROM AUTHOR]

In this study, we sought to elucidate the sequence or events by which mitogenic monoclonal anti-CD3 antibodies (anti-CD3-MoAb) initiate T cell activation. In cultures of monocyte-depleted resting T cells, two anti-CD3-MoAb, OKT3 and anti-Leu 4, induced a state of interleukin 2 (IL-2) receptiveness which culminated in T lymphocyte proliferation when recombinant IL-2 was provided. Evidence that Fc-receptor mediation by monocytes did not contribute to this mitogenesis was supported by studies showing that polyclonal F(ab')2anti-mouse IgG Fc antibody did not alter the magnitude of the IL- 2 driven T cell proliferaitve response, and by the use of T cells from donors whose monocytes were unable to assist in the induction of anti-Leu 4 (IgGl subclass) initiated proliferation. Anti-CD3-MoAb, in the absence of IL-2, induced IL-2 receptor expression on purified T cells, and anti-IL 2 receptor antibodies inhibited T cell proliferation in the presence of this growth factor. Furthermore, following modulation of the CD3 molecular complex in the presence of monocytes, depletion of accessory cells rendered the modulated T cells mitogenically dependent on exogenous IL-2, IL-2 itself did not suffice to promote T cell proliferation in the absence of anti-CD3-MoAb. These results indicate that the binding of monoclonal antibody to CD3 is capable of initiating, in an accessory cell independent manner, premitotic alterations in T cells which can culminate in proliferation when exogenous IL-2 is provided. [ABSTRACT FROM AUTHOR]

Human blood lymphocytes that express Type 3 complement receptors (CR3) can be divided into a major subset with high density Fc receptors for IgG (FcR) identified with the monoclonal antibody Leu 11 and two minor subsets which display either CDS (Leu 2) or CD4 (Leu 3) markers. We isolated CR3+ lymphocyte subsets and examined them for regulatory effects on pokeweed mitogen (PWM) stimulated cells. The FCR+ CR3+ cell suppressed PWM-induced proliferation and Ig production. Pretreatment of these lymphocytes with immune complexes was required to suppress proliferation, but not IgG production. The CR3+ Leu 2+ FCR- subset also had suppressive activity, but this effect was not observed unless the CR3+ Leu 3+ enriched subset was removed. In fact, the CR3+ Leu 3+ enriched subset enhanced IgG synthesis. Brief exposure of CR3+ lymphocytes to recombinant interleukin 2, recombinant α-interferon, but not γ-interferon, markedly enhanced the inhibitory effect. Time course studies and a comparison of inhibition of Ig synthesis with natural killer cell activity suggested that CR3+ lymphocytes act shortly after lymphocytes are exposed to PWM and that Ig production was regulated by suppression rather than cytotoxicity. These CR3+ lymphocyte subsets may have broad antigen non-specific effects on immunoglobulin synthesis. [ABSTRACT FROM AUTHOR]

We investigated nine rhesus monkeys (Macaco mulatta) inoculated with Mycobacterium leprae and three normal human contacts. Peripheral blood monocytes were separated into Fc receptor positive (FcR + ) and Fc receptor negative (FcR-) fractions, and their regulatory role in the lymphoproliferative response in vitro to M. leprae was studied, FcR -- monocytes had strong antigen presentation activity and produced no suppressor effect while FcR+ monocytes had weak antigen presentation activity and produced a non-specific suppressor factor spontaneously. With this assay system we determined that M. leprae-inoculated rhesus monkeys could be divided into three groups: good responders. very weak responders. and non-responders. [ABSTRACT FROM AUTHOR]

During autologous mixed lymphocyte reaction (AMLR) both helper and suppressor T cells capable of regulating B cell responses are generated. The proliferative response of T cells as well as the generation of T suppressor cells in the AMLR of patients with active systemic lupus erythematosus (SLE) is diminished. In contrast, the T helper cells generated in the AMLR show a hyperactivity. The diminished HLA-class II antigen expression observed on non-T cells of SLE origin was restored by treatment of the cells with gamma-interferon (γ-IFN). When tested by immunoglobulin secretion, γ-IFN enhanced T helper cell activity but failed to affect T cell proliferation and T suppressor cell generation in the AMLR derived from patients with SLE. Human recombinant interleukin 2 restores both the proliferative response of T cells and the induction of T suppressor cells in AMLR. [ABSTRACT FROM AUTHOR]

We have earlier isolated, to apparent homogeneity, a 27-28 kD human basic protein (UM) from the urine of a patient with myelomonocytic leukaemia. UM is a mitogen for resting human peripheral blood mononuclear leukocytes (PBML). We have now further defined the effect of UM on human PBML and their subpopulations in 6-day cultures. Cell proliferation was measured by 3H-thymidine uptake and Ig production by the plaque forming cell (PFC) response. Whole PBML responded to UM with proliferation and an increase in PFC. The PFC response was at best equal to and frequently synergistic with that produced by pokeweed mitogen and occurred in the three major Ig classes. To test the effect of UM on subpopulations of PBML, adherent cells (AC) were isolated by plastic adherence and T and B enriched populations by rosetting with sheep red blood cells. The proliferative response of T cells needed the presence of AC whilst the effect on Ig production by B cells required both T cell help and the presence of AC. Human thymocytes also responded to UM by proliferation. The results show that, in addition to being a T cell mitogen, UM is also a T cell dependent polyclonal B cell activator. [ABSTRACT FROM AUTHOR]

In this study we have examined the interactions between accessory cells (AC) and T cells in response to Con A. Highly purified peripheral blood T cells and AC exposed to a variety of treatments were used. We found that untreated AC provided optima! help for T cell proliferation and this was not mediated by soluble factors since whole cells could not be replaced with supernatants from activated AC. Furthermore, cycloheximide-treated AC were able to supply the accessory signal although unable to elaborate soluble activation factors. To find out more about the accesory signal, we examined the ability of monocytes mildly fixed with glutaraldehyde to supply help. These cells were completely unable to perform as AC, although they were viable and had unaltered surface antigen expression. They could not secrete activation factors, but this alone could not explain their inability to supply help because this function was not restored with the addition of soluble activation factors. This indicated that AC-T cell contact was of prime importance to accessory function. To investigate the possibility that AC work by cross-linking structures on the lymphocyte surface, we attempted to substitute for the soluble Con A plus AC with Con A bound to the surface of erythrocytes. Comparable stimulation was observed, suggesting that the cross-linking of Con A-bound structures on the lymphocyte surface generates the accessory signal. [ABSTRACT FROM AUTHOR]

In the burn patient, the mechanisms leading to impaired T lymphocyte activity are unclear. The capacity for T cell proliferation and the expression of Tac antigen (IL-2 receptor) was assessed during the post-burn period in patients with injuries ranging from 5-68%, total body surface area. T cell-dependent (polyclonal) immunoglobulin synthesis, mixed lymphocyte reaction and Interleukin-2 production were also determined in these patients and correlated with survival. Surviving patients demonstrated a transient reduction while terminal patients exhibited a permanent reduction in the number of Tac lymphocytes, unrelated to the absolute number of T cells, during the post-burn period. The reduced percentage of lL-2 receptor-expressing T cells coincided with the suppressed antibody response and reduced alloreactivity. Although the concentration of IL -2 was decreased in all patients throughout the hospitalization period, surviving patients showed a gradual increase in its production while terminal patients gradually decreased to undetectable levels. Exogenous recombinant IL-2 induced a significant enhancement of in-vitro polyclonal immunoglobulin production and blastogenesis in the mixed lymphocyte reaction in immunosuppressed patients who demonstrated up to 50%, reduction in the percentage of IL-2 receptor positive cells. Thus, the reduced capacity for production of and response to lL-2 alter thermal injury may lead to the immunosuppression due to a lack of T lymphocyte clonal expansion. The permanent nature of this detect in patients who died from fatal sepsis may suggest a causative relationship. [ABSTRACT FROM AUTHOR]

Previous studies have shown that male mice of strains with high target organ responsiveness lo androgen, the C57L/J and RF/ J, have lower plasma immunoglobulin levels and weaker antibody responses to protein and polysaccharide antigens than mice of low androgen responder (LAR) strains, the A/J and 129/J. In the current report, the relationship between high androgen responsiveness and low immune performance has been investigated in another strain, the C57BR/edj. Compared Io LAR A/J males. C57BR cdj males had significantly higher target organ responses to androgen as measured by both seminal vesicle bioassay and haematocrit. High androgen responder (HAR C57BR/cdj males were lower than A/J's in PFC responses to sheep red blood cells (SRBC), lipopolysaccharide (LPS) induced spleen cell proliferation and polyclonal B cell activation, HAR C57BR/cdj males were not significantly different from C57BR/cdj females or A/J mice in proliferative responses to concanavalin A (Con A) or phylohaemagglutinin (PHA). These results are compatible with our previous findings in other HAR strains and suggest that the consistently low in vivo immune responses of HAR males may be due lo B cell weakness or T suppressor dysregulation. [ABSTRACT FROM AUTHOR]

Expression of 20-alpha-hydroxysteroid dehydrogenase (20α-SDH), a putative T cell marker in the murine system, has been examined in human haematopoietic cells. Higher levels of enzymatic activity were expressed by human peripheral blood mononuclear cells (PBMC) in comparison with thymocytes. When PBMC were fractionated into T and non T cell subsets, the greatest values of 20α-SDH activity were associated with the non T cell population. Cells from bone marrow exhibited lower levels of 20a-SDH than PBMC and thymocytes. Both myeloid and lymphoid leukaemic cells expressed significant 20α-SDH activity. In addition our data in U-937 and CM-S human cell lines indicate that cells belonging to the myelomonocytic precursor compartment constitutively expressed 20α- SDH activity. Furthermore, this activity was less expressed when these cells were induced to monocyte-macrophage differentiation. In conclusion, our data in the human system indicate that 20α-SDH should not be viewed as a lymphoid lineage-restricted marker enzyme. [ABSTRACT FROM AUTHOR]

The effect of cyclosporine A (CyA) on the expression of the Tac-antigen (IL-2 receptor) on PHA-activated PBMNC was analysed by immunofluorescence. In the initial experiments we determined the number of Tac(+) cells, disregarding cell size; we found that CyA did not affect the number of cells expressing the Tac antigen after lectin stimulation (Fig. 1.Table I), When we found that comparable numbers of Tac(+)-lymphocytes absorbed less lL-2 when grown in CyA as compared to solvent controls, we analysed in more detail the correlation between Tac-antigen expression and cell size of cell populations grown in CyA. It was found that CyA prevented a majority of PHA-activated PBMNC lo undergo blastogenesis despite having expressed the IL-2 receptor, A minority of the cells, however, were refractory to the CyA-mediated suppression of blast formation. Studies analyzing the Tac antigen expression semiquantitatively showed that CyA reduced the intensity of Tac antigen expression on cells of all sizes. [ABSTRACT FROM AUTHOR]

The phenotypic and functional characteristics of the leukaemic cells from one patient with T suppressor ALL were studied at the time of diagnosis and in relapse. At the time of diagnosis, the phenotype corresponded to the intermediate stage between the cortical and medullary phases of normal thymocyte differentiation with a high proportion of T8+ cells (E-R+, TdT+, C3Br-, T3-, T4-, T6+, T8+ +, T10+). Functionally, the cells did not respond to mitogens but mediated strong suppressor activity to allogeneic B-cells, as measured in a reverse haemolytic plaque test. Clinically, the patient exhibited the uncommon feature of hypogammaglobulinaemia. Induction therapy led to complete remission, which continued for 12 months. In the relapse, the phenotype remained essentially stable except for a dramatic decrease of the T8+ cell fraction and an increase of the T10+ cell fraction. Functionally, the suppressor activity was completely lost, indicating a close correlation between phenotype and functional activity in this leukaemic cell population. [ABSTRACT FROM AUTHOR]

Human T lymphocytes cultured in vitro for 5 days with Candida albicans purified polysaccharide (MPPS) produce and antigen non-specific inhibitor (nsINH) which blocks ceil proliferation when added at the beginning of the culture. The antigen presenting function of antigen pulsed adherent cells (macrophages) is significantly impaired by incubation in nsINH. Further analysis shows that nsINH blocks the production of interleukin-1 both from human mononuclear cells stimulated with lipopolysaccharide. Furthermore, the production of interleukin-2 (IL-2) is also suppressed when MPPS stimulated cells are cultured in presence of nsINH. However nsINH does not affect the appearance of lL-2 responsive cells as the addition of gibbon IL-2 to the culture fully reverses the suppressive effect of nsINH on blast transformation. [ABSTRACT FROM AUTHOR]

This study provides evidence that leukaemic B cells are able to proliferate and differentiate into plasmabiasts. The Ig produced was monoclonal in nature and this was shown by gel electrophoresis. [ABSTRACT FROM AUTHOR]

The type of leprosy which develops after infection with Mycobacterium leprae is influenced by the presence or absence of HLA-DR3, as has been demonstrated in an ethnic group originating from Surinum. In the present study we investigated in this same ethnic group the role of HLA-DR. and of HLA-DR3 in particular, in monocyte-T cell interactions during leprosy specific proliferative responses in vitro. HLA-DR3 heterozygous T cells from tuberculoid leprosy patients were cultured with antigen and either HLA-DR3 positive or HLA-DR3 negative homozygous H LA-DR compatible allogeneic monocytes as antigen presenting cells (APCs), T cell proliferative responses with DR3 homozygous monocytes as APCs. were observed to be decreased as compared to T cell proliferative responses with DR3 negative homozygous monocytes as APCs. Furthermore, although the leprosy specific monocyte-T cell interactions were shown to be restricted for HLA-DR, in the anti-MLW-1 response HLA-DR3 appeared to function as a restricting element poorly or not at all. These observations may imply, that an in vitro correlate has been found for an (HLA associated) genetic control of leprosy in vivo. [ABSTRACT FROM AUTHOR]

Interleukin-1 (IL-1) is a monocyte product with diverse amplifying effects on immune cell reactions. We have studied 16 untreated SLE patients to determine the production of IL-1 by their monocytes under the stimulus of E. Coli lipopolysaccharide (LPS) or phorbol myristate acetate (PMA) and measured by the capacity of their supernatants to augment normal autologous mixed lymphocyte cultures (AMLR) or to replace accessory cells in Con A-induced proliferation of T lymphocytes. Concurrently, we studied the response of T lymphocytes from these same patients to IL-1 by its capacity to increase the percentage of stable E rosette forming cells and by the enhancement of T cell proliferation in AMLR. Monocytes from SLE patients produced significantly less IL-l activity than those of age matched controls, regardless of the stimulus (LPS or PMA), as well as of the indicator system. All patients with active disease and seven of the 10 patients with inactive disease had decreased production of IL-1 activity as determined by at least one method. Response of T lymphocytes from SLE patients to IL-1 produced by normal monocytes was also found decreased as compared to normals. This defect was more marked in the T cells from patients with active than in those of patients with inactive disease. These findings indicate that the immunoregulatory disturbance that SLE patients have encompasses monocytes as well as T and B lymphocytes and suggest that the defect is either multicentric or originates in the stem cell. [ABSTRACT FROM AUTHOR]

Among 12 cases of chronic T lymphoproliferative disorders we observed, six patients showed an expansion of mononuclear cells with azurophilic granules usually referred to as large granular lymphocytes or LGL. Cells obtained from five patients with these abnormal LGL proliferations were studied with several surface markers including their reactivity with the HNK-1 monoclonal antibody reported to be specific for LGL. Ceils in four out of five cases were HNK-t positive. Whereas normal LGL have been reported to be unreactive with several T cell markers, three cases showed the co-existence of HNK-1 and surface markers expressed by T cells. Two cases were characterized by the proliferation of OKT8 cells. Cells from one patient were HNK-l positive but did not express T or monocytic antigens. These cells were apparently not completely mature since 2-naphthyl acetate acid esterase activity was negative. Cells from the remaining case were HNK-1 negative and positive for T and monocytic antigens. An increase of OKT-10 cells was observed in only one patient. Our data indicate that proliferations of LGL represent a remarkable proportion of the rare cases of sheep erythrocyte rosetting chronic lymphocytic leukaemias or lymphomas. Besides the morphology of LGL, the rosetting ability and the negativity for peroxidase, cells from these cases showed a vast heterogeneity of other structural and functional markers, possibly reflecting different stages in the maturation of these cells. The HNK-1 monoclonal antibody proved to bean important marker in the identification of these cases. [ABSTRACT FROM AUTHOR]

Peripheral blood mononuclear cells (PBMC), obtained from BCG vaccinated healthy donors, were induced to proliferation by BCG for five days in vitro. When re-exposed to BCG, they failed to proliferate. However, they partially retained the ability to respond to Con A and allogeneic cells. The addition of graded numbers of such cultured cells to fresh autologous PBMC suppressed their proliferative response to BCG. These suppressor cells could also inhibit the proliferation of fresh cells to other mycobacterial antigens, both in particulate form, i.e. Mycobacterium leprae, or in soluble form, i.e. PPD and SPA30. However, these pre-cultured cells did not inhibit the response of fresh cells to non-specific mitogens, i.e. Con A and alloantigens. The inhibition of the response to non-mycobacterial soluble antigens, i.e. tetanus toxoid (TT) and diphtheria toxoid (DT) varied with little suppression in some individuals and stronger suppression in others. The suppression to BCG was found to be mediated by T cells. Subfractionation of T cells by monoclonal antibodies OKT4 and 0KT8 allocated the suppressor cells to the 0KT4+ class of T cells. The suppression in the autologous system was quite strong, whereas it was much weaker in allogeneic systems. [ABSTRACT FROM AUTHOR]

A therapeutic trial of a pan-T monoclonal antibody is described in a patient with a low grade mature T cell proliferation and haemopoietic suppression. The study shows that non-complement fixing IgGl antibodies can be highly effective opsonins, and the dose required can be estimated from in vitro studies. It is demonstrated that therapeutic failure occurred due to the appearance of anti-mouse antibodies and not to anligenic modulation or reticuloendothelial blockade. The literature is reviewed and the potential role of serotherapy in malignant disorders is discussed. [ABSTRACT FROM AUTHOR]

The potent adenosine deaminase inhibitor, deoxycoformycin (dCF), is currently under evaluation in the treatment of lymphoid malignancy. We show that dCF inhibits the growth in soft agar of T cell colonies from PHA stimulated human peripheral blood lymphocytes. In contrast to previous attempts to develop an in vitro model for analysis of the drug's action, concentrations lower than 10-9M are effective, and no 'priming' by pharmacological concentrations of adenosine is required. Maximum inhibition is obtained when dCF is present over the first 4 hr of cellular exposure to PHA. T cells already proliferating in response to PHA are less sensitive to dCF, implying that S-phase events are not primary targets of the drug's action. Colony inhibition does not appear to be due to alteration in the production of, or sensitivity to soluble T cell growth factors. In suspension cultures, dCF at concentrations up to 10-5M fails to inhibit early PHA-induced volume changes, or later mitosis, in peripheral blood lymphocytes. The results show that there is a critical dCF sensitive step early in PHA stimulation. It involves those T cells capable of forming colonies and may be conditioned by the cellular microenvironment. [ABSTRACT FROM AUTHOR]

The capacity of B cells from patients with chronic lymphocytic leukaemia (CLL) to produce and secrete immunoglobulin following mitogen stimulation was investigated using sensitive radioimmunoassays for μ, γ, α, κ and λ immunoglobulin chains. Lymphocytes from seven of the 11 patients studied secreted immunoglobulin in response to pokeweed mitogen (PWM). IgM was always the major immunoglobulin and in five of the seven responders it was the only class detected; only one type of light chain was observed in most cases. This was in contrast to normal lymphocytes which secreted all classes of immunoglobulin (IgM was invariably the lowest) containing both types of light chain. Lipopolysaccharide induced immunoglobulin secretion in only one of four CLL cases. This was again IgM with only one type of light chain. The assays are therefore most probably measuring a response by the leukaemic cells. In most CLL cases, immunoglobulin secretion by the residual normal cells, which proliferate in response to mitogen, was not observed. This inability of the normal lymphocytes to differentiate fully into immunoglobulin secreting cells and the block in switching from IgM production to other classes in the leukaemic cells may both be attributable to a defect in the regulatory system of the immune response in CLL patients. [ABSTRACT FROM AUTHOR]