Search

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 article presents a case study of a 51-year-old man asthma who has a history of dyslipidaemia, hypertension and diabetes. He was diagnosed with leucocytoclastic vasculitis following laboratory histological examinations. The patient received steroid as pulse therapy and oral tapering as treatment for his disease.

Allergen-specific immunotherapy is recognized as a highly effective practice in the treatment of patients with severe allergic rhinitis and/or asthma and is recommended by World Health Organization as an integrated part of allergy management strategy. Several studies have shown that allergen-specific immunotherapy, based on the administration of increasing doses of allergen, achieves a hyposensitization and reduces both early and late responses occurring during the natural exposure to the allergen itself. This is the unique antigen-specific immunomodulatory treatment in current use for human diseases. Successful immunotherapy is associated with reductions in symptoms and medication scores and improved quality of life. After interruption it usually confers long-term remission of symptoms and prevents the onset of new sensitizations in children up to a number of years. Subcutaneous immunotherapy usually suppresses the allergen-induced late response in target organs, likely due to the reduction of the infiltration of T cells, eosinophils, basophils, mast cells and neutrophils. In addition to the reduction of cells of allergic inflammation, immunotherapy also decreases inflammatory mediators at the site of allergen exposure. This review provides an update on the immunological T cell responses induced by conventional subcutaneous and sublingual immunotherapy, and gives a unifying view to reconciling the old dualism between immunoredirecting and immunoregulating mechanisms. [ABSTRACT FROM AUTHOR]

The effect of unstimulated T cell culture supernatants (TCS) from patients with atopic dermatitis and high serum IgE levels on the IgE production in vitro by B cell rich suspensions from normal individuals or grass pollen sensitive patients with mild atopy was evaluated. TCS from patients with raised IgE enabled B cell suspensions from normal individuals to produce detectable amounts of IgE and potentiated the spontaneous IgE synthesis in vitro by B cell suspensions from grass sensitive patients. In contrast, the addition of TCS from normal subjects with low serum IgE levels did not increase or even reduced IgE synthesis by B cell cultures. When the same B cell cultures were analysed for their ability to produce IgG or IgM protein, no significant differences were observed. These findings indicate that T lymphocytes from patients with high serum IgE levels can release soluble factor(s) possessing isotype (IgE) specific potentiating activity. [ABSTRACT FROM AUTHOR]

IgE protein and grass-specific IgE antibodies were detected in the supernatants of 7-day cultures of unstimulated and pokeweed mitogen (PWM) stimulated human blood mononuclear cells from non-atopic and grass pollen-sensitive individuals. Significant amounts of IgE protein were detected in culture supernatants of grass-sensitive individuals and, even at lower levels, in those of non-atopic subjects In contrast, detectable amounts of grass-specific antibodies were found only in the culture supernatants of grass-sensitive subjects. The mean values of total and grass-specific IgE detected in the supernatants of unstimulated and PWM-stimulated cultures did not differ statistically. Time sequence studies showed that IgE concentrations, measured in the 7-day supernatants. were due to a continuous release from the cells of IgE quantities progressively decreasing up to days 7 or 8. Comparison of the IgE protein and IgE antibody found in the 7-dayculturesupernatants to those released from initial cell pellets by treatment with acid buffer or freezing and thawing, showed that the IgE detected in 7-day supernatants could result, in part, from the release of cytophilic IgE bound to basophil or other cell types and in part also from the release of preformed lymphocyte cytoplasmic IgE into the supernatant fluids during the course of culture. In most non-atopic subjects and in some grass-sensitive patients the preformed IgE accounted virtually for the total IgE detected in the 7-day culture supernatants. However, the increase of IgE above the levels measured in the initial cell pellets, which was found inmost grass-sensitive subjects, clearly reflected newly synthesized IgE. Both cycloheximide and puromycin were capable of reducing significantly the IgE concentration in culture supernatants when it was greater than the amount found in the initial cell pellets. The treatment of cells with mitomycin C was also able to decrease significantly the amount of IgE released in the supernatant after day 3 of culture. [ABSTRACT FROM AUTHOR]

Some properties of the receptor for IgM on human lymphocytes have been investigated. It was shown that the interaction of native IgM with the receptor present on T and B lymphocytes is not critical for its detection in the EAM-rosette assay. In fact, high values of EAM-RFC could be found on cell suspensions cultured overnight in either IgM-free or IgM-containing media. In addition, the inhibition of EAM-rosettes by human monoclonal IgM at 37°C was not as effective as at 4°C. Rabbit IgM showed a significantly greater ability to inhibit the binding of antigen-IgM antibody complexes than human IgM. The receptor for IgM was easily removed by handling procedures, the incubation of lymphocytes at 4°C and treatment of the cells with low concentrations of trypsin or pronase. After the enzymatic treatment, a rapid resynthesis occurred, which restored the number of EAM-rosettes formed by T cells and significantly increased the number formed by B cells. The interaction between the receptor and antigen-IgM antibody complexes stopped the spontaneous shedding of the receptor at 4°C. When the incubation of the cells with immune complexes was performed at 37°C, a .significantly different behaviour between T cells equipped with receptor for IgM and those possessing receptor for IgG was found. After the binding of EAG to the receptor for IgG, a process of rapid dissociation of rosettes occurred, whereas the incubation with EAM did not induce an irreversible loss of the receptor for IgM. [ABSTRACT FROM AUTHOR]

Receptors for IgM were detected on peripheral blood and tonsil human lymphocytes by a rosette technique with ox red blood cells (ORBC) coated with anti-ORBC rabbit IgM. It was found that the receptors are very sensitive to handling procedures of cells and to low temperatures. An overnight incubation period at 37°C was the optimal condition for the maximum expression of receptors for IgM, but the use of IgM-free media in these cultures was neither an essential nor favourable factor for an optimal rosette formation, when ORBC heavily coated with rabbit IgM were used. The great majority of chronic lymphocytic leukaemia (CLL) patients presented a high number of EA(IgM)-RFC, either on freshly drawn or cultured lymphocytes. By fractionation procedures of normal peripheral blood and tonsil lymphocytes, it was found that a subpopulation of B cells, like T cells, also possess receptors for IgM. The receptors for IgM on B cells are less easily detectable and seem to possess a lower avidity for IgM than those present on T lymphocytes. [ABSTRACT FROM AUTHOR]

Purified B lymphocytes obtained from human tonsil cell populations by removing; E. rosette-forming cells by density sedimentation did not proliferate at three days in response to PHA and Con A, but showed a significant ³H-labelled thymidine incorporation when the PHA response was assessed at day 6 of culture. The 6th-day response, which was completely abolished by the reduction of T-cell contamination to less than 0-1% by re-rosetting and a second separation, was due in part to a direct activation by PHA of contaminating T cells and in part to a T cell-mediated B-cell response. When purified B cells were stimulated for 3 days by PHA in the presence of an equal number of autologous or homologous mitomycin-treated T lymphocytes a highly significant uptake of ³H-labelled thymidine was demonstrated. The majority of List cells obtained at day 4 in these cultures were unable to form E rosettes and showed surface immunoglobulin by immuno-fluorescence stain. This response was markedly decreased by previous treatment of B cells with mitomycin C and it was abolished when B cells were killed by heating at 56°C for 1 hr. Purified B lymphocytes from human tonsils did not respond in vitro when cultured for 6 days in the presence of soluble antigens (PPD and Candida). However, a highly significant response to the same antigens could be demonstrated when B cells were cultured in the presence of autologous mitomycin-treated T cells. These models of T-B co-operation could provide an interesting tool for studying the differentiation and antibody production in vitro of human B lymphocytes. [ABSTRACT FROM AUTHOR]

We have previously demonstrated that a proportion of human T cell clones (TCC) derived from tonsil or peripheral blood (PB) of non-allergic donors, upon triggering with phytohaemagglutinin (PHA) or anti-CD3 monoclonal antibody (MoAb), were able to provide help for IgE synthesis in B cells from both allergic and non-allergic individuals. In this study we show that, upon PHA stimulation, culture supernatants from 10 selected TCC active on IgE synthesis also provided helper activity for IgE, whereas supernatants from unstimulated cultures of the same TCC were ineffective. In contrast, culture supernatants derived from five PHA-stimulated TCC, unable to provide helper function for IgE synthesis, consistently failed to elicit production of IgE. While the induction of IgE synthesis by TCC occurred in B cells from virtually all allergic and non-allergic donors, their soluble factor(s) were found to be able to provide substantial help for IgE production only in B cells from a proportion of donors tested. In addition B cells from non-atopic donors usually appeared to be less responsive than atopic B cells to the activity of such factor(s). In contrast, synthesis of both IgG and IgM was induced in every B cell donor by both TCC and their supernatants. Partial characterization of the factor(s) providing helper function for IgE synthesis in B cells showed that it apparently had a mol. wt between 10 and 50 kD and did not bind to immobilized IgE. Such an activity appeared to be associated with the presence of interleukin 4 (IL-4) in supernatants and it was inhibited by adding both gamma-interferon and anti-human IL-4 antibody in culture. [ABSTRACT FROM AUTHOR]

High proportions of T8+ cells with inverted T4/T8 ratio were found in freshly isolated thyroid lymphocytes from patients with Hashimoto's thyroiditis. In addition, about one third of thyroid infiltrating cells expressed the TAC antigen, whereas in patient peripheral blood (PB) or normal lymphocytes from PB or lymphoid organs the percentage of TAC-positive cells was consistently lower than 10%. Following negative selection with OKT4 or OKT8 monoclonal antibodies and complement, TAC+ T cells were enriched in the T8+ cell population. Thyroid infiltrating T cells from two patients underwent two different cloning procedures. In the first, single T cells were initially activated with phytohaemagglutinin (PHA) and interleukin 2 (IL-2), in the other with recombinant IL-2 (rIL-2) alone. The majority of T cell clones obtained by initial PHA-stimulation (55 - 65%) had the T8+ phenotype, but the frequency of T8+ clones obtained by stimulating T cells with rIL-2 alone was even higher (78 & 71%, respectively). The majority of T8+ clones elicited by PHA (35/37 & 36/38) and all the T8+ clones (36/ 36 & 22/22) obtained from thyroid infiltrates with initial stimulation by rIL-2 displayed cytolytic activity, Most of cytolytic T8+ clones obtained from thyroid infiltrates with both cloning procedures, displayed NK activity against human K562and MOLT-4 target cells, but not against a NK-resistant target, such as Raji cells. These data suggest that in Hashimoto's disease a considerable proportion of thyroid infiltrating T cells are in vivo activated T8+ cytolytic T cells with N K activity, which may be of importance in determining or maintaining the tissue damage of the target gland. [ABSTRACT FROM AUTHOR]

Peripheral blood mononuclear cells from atopic donors were stimulated in vitro with allergens (Rye group I or Dermatophagoides pteronyssinus). T cell lines were originated and maintained in long term culture using lL-2 and periodical restimulations with allergen. The lines were antigen specific (i.e. responded to the allergen used to raise them and not to other antigens) and required that the antigen was presented by autologous cells (i.e. they were restricted). The restriction elements were probably at the level of HLA-DR antigens since the proliferative response was specifically blocked by anti-HLA-DR antibodies. Surface marker analysis revealed that the lines comprised mainly cells with an helper/inducer phenotype, although cells with markers of the suppressor/cytotoxic T cells were also present. The lines could be cloned by limiting dilution and clones with the same restriction and specificity as the parental line were isolated. These studies demonstrate the possibility of obtaining a large number of allergen specific human T cells that can be used for further in vitro studies on the regulation of the IgE response. [ABSTRACT FROM AUTHOR]

Peripheral blood lymphocytes (PBL) from a proportion of grass-sensitive patients. studied during or immediately after the grass pollination period, showed spontaneous production in vitro of grass-specific IgE antibody, whereas PBL from atopic patients sensitive to allergens other than grass pollens or non-atopic individuals did not. Pre-incubation of IgE antibody producing PBL from grass-sensitive patients with minute amounts of a mixed grass pollen (MGP) extract or Rye grass antigen Group I (Rye I) usually resulted in a reduction of the spontaneous production in vitro of IgE protein and in a marked inhibition of the spontaneous production in vitro of grass-specific IgE antibody. This antigen-specific inhibition was not mediated by T lymphocytes, but it was apparently due to a signal directly delivered by antigen to the spontaneously IgE antibody producing cells. The results support the concept that the activity of cells responsible for the persistent IgE antibody formation in vitro in atopic patients can be modulated by antigen. [ABSTRACT FROM AUTHOR]

The presence of surface membrane IgE (SmIgE)-bearing cells in the peripheral blood (PB) of atopic patients was investigated by the use of isotype-specific rosettes of human red blood cells coupled to immunosorbent-purified rabbit or monoclonal mouse antibodies against human IgE (R or M anti-∊-HRBC). After dissociation of cell bound IgE by treatment with acid buffer. 21±0.3% and 1.2±0.3%, circulating non-T, non-phagocytic. cells from atopic patients were still capable of forming rosettes with R or M anti-IgE-HRBC-respectively. IgE molecules detectable on cells after dissociation of cytophilic IgE were quite resistant, like surface membrane IgM (SmIgM), to treatment with proteolytic enzymes, but they were removed under capping conditions by soluble anti-IgE antisera. All SmIgE-bearing (IgE+) cells also bore DR determinants, but many of them lacked SmIgM. Depletion of IgE+ cells strongly reduced the ability of PB lymphocyte suspensions from atopic patients to produce spontaneously IgE protein in vitro. Likewise. depletion of cells bearing DR determinants (DR+ cells) resulted in a marked decrease of the spontaneous IgE biosynthesis, whereas depletion of SmIgM-bearing (IgM+) cells had no effect. These data suggest that cells mainly implicated in the spontaneous IgE production in vitro seen in atopic patients are DR+ IgE+ IgM- circulating lymphocytes. [ABSTRACT FROM AUTHOR]

Studies in mice have initially suggested that Th17 cells are the pathogenic cells in autoimmune disorders, whereas Th1 cells may behave rather as protective. Subsequent studies in humans have demonstrated the existence of Th cells able to produce both IL-17 and IFN-gamma (Th17/Th1), as well as the plasticity of Th17 cells, i.e. their property to shift to Th1 in presence of IL-12. The plasticity of Th17 to Th1 cells was recently confirmed in mice, where it was even found that Th17 cells behave as pathogenic only when they shift to Th1 cells. Studies in humans have also shown that memory Th17 are different than in mice because virtually all of them express CD161. A positive correlation between presence of CD4+ CD161+ T cells in the synovial fluid of children with juvenile idiopathic arthritis and indicators of disease activity was found. They were Th17/Th1 and Th1 cells originated from local shifting of Th17 cells to IFN-gamma poduction. While murine Th17 cells are thought to derive from naive CD4+ T cells in response to IL-6 and TGF-beta, human Th17 cells originate from thymic CD4+ CD161+ T-cell precursors in response to IL-1b and IL-23. TGF-beta indirectly favours development of human Th17 cells through the inhibition of both T-bet expression and development of Th1 cells. Very recently, Th17 cells have been detected in the thymus of wild-type mice and TGF-beta was found to be dispensable also for murine Th17 differentiation. Thus, studies in humans have depicted Th17 cells better than studies in mice. [ABSTRACT FROM PUBLISHER]