Search

Background Aims: Key obstacles in human iNKT cell translational research and immunotherapy include the lack of robust protocols for dependable expansion of human iNKT cells and the paucity of data on phenotypes in post-expanded cells., Methods: We delineate expansion methods using interleukin (IL)-2, IL-7 and allogeneic feeder cells and anti-CD2/CD3/CD28 stimulation by which to dependably augment Th2 polarization and direct cytotoxicity of human peripheral blood CD3 + Vα24 + Vβ11 + iNKT cells., Results: Gene and protein expression profiling demonstrated augmented Th2 cytokine secretion (IL-4, IL-5, IL-13) in expanded iNKT cells stimulated with anti-CD2/CD3/CD28 antibodies. Cytotoxic effector molecules including granzyme B were increased in expanded iNKT cells after CD2/CD3/CD28 stimulation. Direct cytotoxicity assays using unstimulated expanded iNKT cell effectors revealed α-galactosyl ceramide (α-GalCer)-dependent killing of the T-ALL cell line Jurkat. Moreover, CD2/CD3/CD28 stimulation of expanded iNKT cells augmented their (α-GalCer-independent) killing of Jurkat cells. Co-culture of expanded iNKT cells with stimulated responder cells confirmed contact-dependent inhibition of activated CD4 + and CD8 + responder T cells., Discussion: These data establish a robust protocol to expand and novel pathways to enhance Th2 cytokine secretion and direct cytotoxicity in human iNKT cells, findings with direct implications for autoimmunity, vaccine augmentation and anti-infective immunity, cancer immunotherapy and transplantation., (Copyright © 2020 International Society for Cell and Gene Therapy. Published by Elsevier Inc. All rights reserved.)

T11 target structure (T11TS), a membrane glycoprotein has been documented with anti neoplastic activity in glioma bearing animal model in our lab. In this study, we have evaluated the phagocytic potential, expression of VEGF, TNF-α in T11TS treated and untreated macrophages in all four grades of glioma. The data indicates the significant enhancement of phagocytosis in T11TS treated macrophages of grades I and II glioma. There was significant up regulation in TNF-α and significant down regulation in VEGF expression in T11TS treated macrophages in grade I and II glioma. We also attempted to know any possible apoptotic role of T11TS in tumor cells by comparing Bax and Bcl2 in treated and untreated tumor cells of all four grades. We found significant up regulation in Bax expression and down regulation in Bcl2 expression of grades I and II glioma. The outcome may help in pushing this molecule into pharmaceutical domain., (Copyright © 2013 Elsevier Inc. All rights reserved.)

The tumor necrosis factor (TNF)-family cytokine TL1A (TNFSF15) costimulates T cells through its receptor DR3 (TNFRSF25) and is required for autoimmune pathology driven by diverse T-cell subsets. TL1A has been linked to human inflammatory bowel disease (IBD), but its pathogenic role is not known. We generated transgenic mice that constitutively express TL1A in T cells or dendritic cells. These mice spontaneously develop IL-13-dependent inflammatory small bowel pathology that strikingly resembles the intestinal response to nematode infections. These changes were dependent on the presence of a polyclonal T-cell receptor (TCR) repertoire, suggesting that they are driven by components in the intestinal flora. Forkhead box P3 (FoxP3)-positive regulatory T cells (Tregs) were present in increased numbers despite the fact that TL1A suppresses the generation of inducible Tregs. Finally, blocking TL1A-DR3 interactions abrogates 2,4,6 trinitrobenzenesulfonic acid (TNBS) colitis, indicating that these interactions influence other causes of intestinal inflammation as well. These results establish a novel link between TL1A and interleukin 13 (IL-13) responses that results in small intestinal inflammation, and also establish that TL1A-DR3 interactions are necessary and sufficient for T cell-dependent IBD.

The CD48 molecule is a glycosyl-phosphatidyl-inositol (GPI)-anchored cell-surface protein of the CD2 family of molecules. Originally described on virally-induced B cells, CD48 has been found on various hematopoietic cells, and its expression is regulated by viral and bacterial products and immune-associated proteins. CD48 binds CD2 and other molecules, yet its high-affinity ligand in both mouse and human systems is 2B4. Despite its lack of an intracellular domain, stimulation of CD48 induces rearrangement of signaling factors in lipid rafts, Lck-kinase activity, and tyrosine phosphorylation. As an adhesion and co-stimulatory molecule, CD48 induces numerous effects in B and T lymphocytes, natural killer cells, mast cells, and eosinophils. Some of these depend upon cell-cell interactions via 2B4-CD48 binding. The structural and phenotypic characteristics of CD48, and its role in physiological and pathophysiological processes, are reviewed herein. Possible CD48-based applications for immune-impaired and inflammatory disorders are discussed as well., (Copyright © 2010 Elsevier Ltd. All rights reserved.)

The SLAM/CD2 gene family encodes receptors that play important roles in regulating multiple cellular interactions in the adaptive and innate immune systems. Three members of this gene family, Ly108, Ly9, and CD84, exhibit polymorphisms that strongly influence susceptibility to systemic autoimmunity, notably in mice, but also in some human populations. Polymorphisms of Ly108 in mice strongly impact central tolerance in both B and T cell development, predominantly by modulating apoptosis, anergy, and cell-cycle progression. In addition, Ly108 and CD84, together with their downstream signaling adaptor SLAM-associated protein (SAP), have emerged as key players in B-T interactions during the formation of germinal centers. Interestingly, several independent lines of research have now associated variations in B-T interactions during germinal center formation with systemic autoimmunity, suggesting that susceptibility to systemic lupus erythematosus (SLE) may involve in part the impairment of this peripheral tolerance checkpoint. These new insights into the multiplicity of roles played by the SLAM/CD2 family and its potential importance in human autoimmunity positions the SLAM/CD2 family as an excellent target for immunotherapy., (Copyright © 2010 Elsevier Ltd. All rights reserved.)

Thymus xenotransplantation has been shown to induce tolerance to porcine xenografts in mice and to permit survival of alpha1,3Gal-transferase knockout porcine kidney xenografts for months in nonhuman primates. We evaluated the ability of porcine thymus xenotransplantation to induce human T-cell tolerance using a humanized mouse (hu-mouse) model, where a human immune system is preestablished by implantation of fetal human thymus tissue under the kidney capsule and intravenous injection of CD34(+) hematopoietic stem/progenitor cells. Human T-cell depletion with an anti-CD2 mAb following surgical removal of human thymic grafts prevented the initial rejection of porcine thymic xenografts in hu-mice. In these hu-mice, porcine thymic grafts were capable of supporting human thymopoiesis and T-cell development, and inducing human T-cell tolerance to porcine xenoantigens. Human T cells from these mice responded strongly to third-party pig, but not to the thymic donor swine leukocyte antigen (SLA)-matched pig stimulators in a mixed lymphocyte reaction (MLR) assay. Anti-pig xenoreactive antibodies declined in these hu-mice, whereas antibody levels increased in nontolerant animals that rejected porcine thymus grafts. These data show that porcine thymic xenotransplantation can induce donor-specific tolerance in immunocompetent hu-mice, supporting this approach for tolerance induction in clinical xenotransplantation.

Analysis of the NK cell developmental pathway suggests that CD2 expression may be important in regulating NK maturation. To test this hypothesis, we developed mice containing only an inhibitory CD2 molecule by linking the extracellular domain of CD2 to an intracellular immunoreceptor tyrosine-based inhibitory motif (ITIM) motif. Mice containing the CD2 Tg(ITIM) transgene, introduced into a CD2 KO background, have no morphologically detectable lymph nodes, although development of the thymus appears normal. In addition, these mice had major loss of both NK and NKT subsets in peripheral organs, while T and B cell frequencies were intact. Expression of CD2 was low on T cells and lacking on B cells and functional defects were observed in these populations. NKT cells expressing CD4 were absent, while the CD8+ and double negative NKT cells were retained. Small subsets of NK cells were detected but expression of CD2 on these cells was very low or absent, and their maturation was impaired. Based on the phenotype described here, we believe that these mice represent a unique model to study lymphoid organ and lymphocyte development.

2B4 belongs to the CD2 subset of the IgG family of receptors. Members in this family have been shown to function as coreceptors via homophilic or heterophilic interactions. Both 2B4 and CD2 bind to CD48, another member of this family. Because all 3 molecules are expressed on natural killer (NK) cells, it raises a possibility that the binding of 2B4 and CD2 to CD48 among NK cells may have functional consequences. Using specific monoclonal antibodies and gene-deficient NK cells, we found that 2B4/CD48, but not CD2/CD48, interaction is essential for IL-2-driven expansion and activation of murine NK cells. In the absence of 2B4/CD48 interaction, NK cytotoxicity and IFN-gamma secretion on tumor target exposure is severely impaired. Impaired activation of NK cells in 2B4-deficient mice was also demonstrated by poor NK-mediated clearance of syngeneic tumor cells in these mice. Functional impairment of NK cells in the absence of 2B4/CD48 interactions was accompanied by defective calcium signaling, suggesting that the early signaling pathway of NK receptors is inhibited. Finally, homotypic interactions among NK cells through 2B4/CD48 was visualized by specific localization of GFP-tagged 2B4 onto NK-NK conjugation sites. Thus, these data identify a novel mechanism whereby NK effector function is regulated via homotypic 2B4/CD48 interactions.

The immunoglobulin CD2 is a cell adhesion molecule that mediates T-cell activation by binding to its receptor CD58 on antigen-presenting cells (APCs). Modulation or inhibition of this interaction has been shown to be therapeutically useful. E-rosetting assay is usually applied in the study of the modulation of CD2-CD58 interaction. In this study, we demonstrated a novel, rapid and sensitive heterotypic cell adhesion assay for CD2-CD58 interaction. The CD2 expression on the surface of Jurkat cells and the CD58 expression on the Caco-2 cells were confirmed by flow cytometry and ELISA studies, respectively. Then Jurkat cells were fluorescent-labeled with 2 microM of BCECF-AM for 45 min at 37 degrees C before adding to confluent Caco-2 monolayers cultured in 96-well culture dishes. After 30 min, non-adherent Jurkat cells were removed by washing with PBS, while the monolayer-associated Jurkat cells were lysed with 0.5 ml of 2% Triton X-100 in 0.1 M NaOH. Fluorescence (FL) was quantitated using a microplate fluorescence analyzer with BCECF's excitation maximum of 485 nm and emission maximum of 535 nm. This method was successfully applied for testing inhibitory peptides to CD2-CD58 interaction.

Nitrosocompounds formed by the interaction of nitrites and secondary amines are neurotoxic in human and different rodent species. Human exposure of nitrosocompounds are widespread affected by different modes like nitrite/nitrate preserved foods, beverages like beer, formed in the stomach following uptake of the precursors nitrates, nitrites and secondary amines. The productions of alkylating metabolites during the breakdown of nitrosocompounds are the causative agents for the neurotoxic changes of the neural cells. An attempt has been made in our lab to study the effect of nitrosocompound mediated toxicity and the gradual toxic effects of these neurotoxic agents to transform the normal glial cells to a neoplastic one. The present study indicated that a transmembrane glycopeptide of sheep red blood cell (SRBC), known as S-LFA3 or T11 target structure (T11TS) applied to nitrosocompound induced animals manifesting a full grown intracranial malignancy can revert back tumor-bearing condition to the normal physiological state. Young Druckray rat of both sexes aging 3-5 days were injected with N'-N'-ethyl nitrosourea (ENU) intraperitoneally (i.p.) at a single dose of 80 mg/kg body weight to simulate nitrosocompound mediated neurotoxicity. 2-,4-, 6-, 8-, and 10-month-old neonatal ENU induced animals were sacrificed for growth kinetics, functional immunological parameters and receptor studies to hint at the changes during tumor development. In order to determine the immunomodulatory role of T11TS, 7-month-old ENU induced animals were injected with T11TS at a dose of 0.41 mg/kg body weight, in three consecutive doses at an interval of 6 days maintaining normal control as untreated control and ENU induced animals of age-matched rats as tumor-bearing control. All the immunological parameters, growth kinetic study, receptor-based study by FACS directly established the immunomodulatory, anti-toxic and anti-tumor property of T11TS/S-LFA3. Finally, formation of DNA ladder along with the FACS-based apoptosis study clearly indicated that T11TS is a potent apoptotic inducer in neoplastic neural cells.

CD2 is expressed on T cells and NK cells and is important in T cell activation, making it a potential target for immune intervention. Here, we report a series of experiments aimed at defining the ability of mAbs directed against the CD2 molecule to prevent cardiac allograft rejection in low and high responder rat strain combinations. Administration of the mouse anti-rat CD2 mAbs OX34 or OX55 around the time of transplantation prolonged survival of fully allogeneic Lewis (RT1l) cardiac allografts in low responder DA (RT1a) recipients (MST 14 days for OX55 and >100 days for OX34). Treatment with OX34 prolonged graft survival in the reciprocal high responder DA to Lewis rat strain combination (MST 19 days) and when combined with CTLA4-Ig resulted in long-term graft survival (MST>100 days). Despite these in vivo effects, OX34 had little effect on in vitro assays of lymphocyte activation. Instead, the ability of OX34 to extend allograft survival correlated with T cell depletion. Administration of OX34 induced a similar degree of CD4 T cell depletion in DA and Lewis recipients, but the CD4 depletion observed was more transient in Lewis recipients. Lewis, but not DA strain rats, developed an anti-murine Ig response. Combined treatment with CTLA4-Ig abolished the anti-globulin response to OX34 in Lewis recipients, prolonged circulation of OX34 and increased the extent and duration of CD4 depletion. We conclude that anti-CD2 treatment effectively prolongs cardiac allograft survival and addition of CTLA4-Ig increases its efficacy by abrogating the production of neutralising antibodies.

The extent of interaction between human T-lymphocytes and xenogeneic antigen-presenting cells (APCs) is species-dependent. A successful interaction requires high-affinity receptor-ligand pairing across species and recognition of antigens presented by foreign major histocompatibility complex (MHC). A deficient human T-lymphocyte response to xenogeneic cells is likely the result of a defect in these interactions. However, the requirements for a T-cell response to superantigen (SAg) may differ from those of other T-cell responses. Using irradiated murine splenocytes, which are believed to be incapable of eliciting human T-cell responses, and porcine aortic endothelial cells (PAECs) as the APC populations, we studied the human T-lymphocyte response to antigens presented by these cells. Direct proliferation of human T-lymphocytes to SAg presented by murine APCs was demonstrated; it was blocked by anti-human LFA-1 and anti-murine MHC class II but not by anti-human MHC class II. PAECs also presented SAg to human T-cells, generating a proliferative response greater than the primary response to porcine xenoantigen. Culture of human T-cells with murine splenocytes or PAECs and SAg Staphylococcus enterotoxin A (SEA) for 7 days primed human T-cells to proliferate in a secondary culture in response to autologous APCs. This autologous secondary response was human MHC class II-dependent and was inhibited by anti-human LFA-1, anti-human CD2, and anti-human CD98. Surprisingly, both of these responses were also blocked by anti-SEA, suggesting that despite vigorous washing, a small amount of functionally important SAg was carried over from primary to secondary culture, probably bound to the surface of T-cells. Xenogeneic APCs, even those that fail to stimulate human T-cells directly, can serve as APCs for primary human T-cell responses. After such interactions T-cells can develop secondary responses in autologous interactions based on retention of minute amounts of SAg. Such interactions may have important implications for xenotransplantation.

Adult T-cell leukemia (ATL) develops in a small proportion of individuals infected with the retrovirus human T-cell leukemia virus (HTLV-1). We evaluated the efficacy of MEDI-507 (a humanized monoclonal antibody directed against CD2) alone and in combination with humanized anti-Tac (HAT) directed toward CD25, the interleukin-2 receptor alpha (IL-2Ralpha) using a human adult T-cell leukemia xenograft model. Weekly treatments (4) with HAT significantly prolonged the survival of the ATL-bearing mice when compared with phosphate-buffered saline (PBS)-treated controls (P <.0001). Mice treated with MEDI-507 (100 microg/wk for 4 weeks) survived longer than those treated with HAT (P <.0025). Furthermore, prolonged treatment (6 months) of ATL with MEDI-507 significantly improved the outcome when compared with a short course (4 weeks) of therapy (P <.0036). Such treatment with weekly MEDI-507 for 6 months led to a prolonged survival of the ATL-bearing mice that was comparable with the survival observed in the control group of mice that did not receive a tumor or therapeutic agent. We also found that the expression of Fcgamma receptors (FcRgamma) on polymorphonuclear leukocytes and monocytes was required for MEDI-507-mediated tumor killing in vivo. Thus, the tumor-killing mechanism with MEDI-507 in vivo required the expression of the receptor FcRgammaIII on polymorphonuclear leukocytes and monocytes, suggesting that it is mediated by a form of antibody-dependent cellular cytotoxicity. These results demonstrate that MEDI-507 has therapeutic efficacy on ATL in vivo and provides support for a clinical trial involving this monoclonal antibody in the treatment of patients with CD2-expressing leukemias and lymphomas.

Red blood cells (RBC) are known to modulate T cell proliferation and function possibly through downregulation of oxidative stress. By examining parameters of activation, division, and cell death in vitro, we show evidence that the increase in survival afforded by RBC is due to the maintenance of the proliferative capacity of the activated T cells. We also show that the CD3+CD8+ T cell subset was preferentially expanded and rescued from apoptosis both in bulk peripheral blood lymphocyte cultures and with highly purified CD8+ T cells. The ability of RBC to induce survival of dividing T cells was not affected by blocking the CD58/CD2 interaction. Moreover, addition of hemoglobin, heme or protoporphyrin IX to cultures of activated T cells did not reproduce the effect of intact RBC. Considering that RBC circulate throughout the body, they could play a biological role in the modulation of T cell differentiation and survival in places of active cell division. Neither CD58 nor the heme compounds studied seem to play a direct relevant role in the modulation of T cell survival.

CD2 and 2B4 (CD244) are members of the immunoglobulin gene superfamily and are both ligands for another family member, CD48. CD2 is widely distributed on T, NK, and B cells and some antigen-presenting cells, while 2B4 is expressed on NK and some T cells and monocytes and is known to participate in NK cytotoxicity. Since indefinite allograft survival could be obtained by a combination of anti-CD48 plus anti-CD2 mAb administration, it was important to determine the role of 2B4 blockade in allograft rejection. MAbs directed against CD2, CD48, or 2B4 were administered singly or in pairs to cardiac allograft recipients. The experiments show that only anti-CD2 plus anti-CD48 mAbs result in indefinite allograft survival, while anti-CD2 plus anti-2B4 mAbs substantially prolong graft survival, and anti-CD48 plus anti-2B4 mAbs were no better than each mAb alone. The effect of these mAbs on anti-CD3 mAb and alloantigen-driven proliferation and IFN-gamma production were also assessed. In general, anti-CD2 inhibited both anti-CD3 mAb and alloantigen-driven responses, while anti-CD48 inhibited only anti-CD3 mAb but not alloantigen-driven proliferative and cytokine responses. Anti-2B4 mAbs were generally ineffective alone. Combinations of mAbs were more effective than single mAbs only in alloantigen-driven proliferation, commensurate with allograft survival results. Using CD2-/- and CD48-/- T cells and antigen-presenting cells, we also demonstrate that these inhibitory mAbs act primarily by blocking intercellular interactions, rather than directly delivering negative signals to T cells. These results suggest that, unlike CD2, 2B4 is not a potent regulatory molecule or ligand for CD48 in the response to alloantigen. Blocking the 2B4-CD48 receptor-ligand pair does not inhibit T-cell responses and alloreactivity to the same degree as CD2-CD48 blockade.

Background: DC generated from monocytes have been used for vaccines. We have developed a monocyte enrichment procedure by depleting T and B cells with anti-CD2 and anti-CD19 Abs using the automated Isolex 300i magnetic cell selector for clinical-scale DC generation in gas permeable SteriCell culture bags. We have also compared DC function, yield and purity of DC generated from adherent monocytes using culture bags in a closed system, with DC generated in conventional tissue culture flasks., Methods: Monocytes were enriched from normal donor apheresis products using CD2/19 depletion with experimental software on the Isolex 300i (ISO), adherence (AD) to SteriCell bags and to T175 flasks and then cultured for 7 days in serum-free X-VIVO 15 media with GM-CSF and IL-4. Phenotype and dextran uptake were analyzed by flow cytometry and allogeneic MLR was also evaluated., Results: ISO-DC and AD-DC from SteriCell bags showed similar viability. Higher purity of ISO-DC than AD-DC was measured by forward- and side-scatter flow cytometry. Similar expression of CD1a, CD80, CD86 and CD83 were observed in both ISO-DC and AD-DC. Similar dextran uptake and allo MLR were also observed., Discussion: These data indicated that functional DC were generated in gas permeable SteriCell culture bags from both ISO- and AD-monocytes in a closed system.

The ability of human gamma delta-T cells to mediate a number of in vitro functions, including innate antitumor and antiviral activity, suggests these cells can be exploited in selected examples of adoptive immunotherapy. To date, however, studies to examine such issues on a clinical scale have not been possible, owing in large measure to the difficulty of obtaining sufficient numbers of viable human gamma delta-T cells given their relative infrequency in readily available tissues. Standard methods used to expand human T cells often use a combination of mitogens, such as anti-T-cell receptor antibody OKT3 and interleukin (IL)-2. These stimuli, though promoting the expansion of alpha beta-T cells, usually do not promote the efficient expansion of gamma delta-T cells. CD2-mediated, IL-12-dependent signals that result in the selective expansion of human gamma delta-T cells from cultures of mitogen-stimulated human peripheral blood mononuclear cells are identified. It is first established that human gamma delta-T cells are exquisitely sensitive to apoptosis induced by T-cell mitogens OKT3 and IL-2. Next it is shown that the CD2-mediated IL-12-dependent signals, which lead to the expansion of gamma delta-T cells, do so by selectively protecting subsets of human gamma delta-T cells from mitogen-induced apoptosis. Finally, it is demonstrated that apoptosis-resistant gamma delta-T cells are capable of mediating significant antitumor cytotoxicity against a panel of human-derived tumor cell lines in vitro. Both the biologic and the practical implications of induced resistance to apoptosis in gamma delta-T cells are considered and discussed because these findings may play a role in the development of new forms of adoptive cellular immunotherapy. (Blood. 2000;96:3827-3837)

Activation of T cells can be initiated through cell surface molecules in addition to the T-cell receptor-CD3 (TCR-CD3) complex. In human T cells, ligation of the CD2 molecule by mitogenic pairs of anti-CD2 monoclonal antibodies activates T cells via biochemical signaling pathways similar but not identical to those elicited on TCR engagement. This study describes a key role for the p36/38 membrane adapter protein linker for T cell activation (LAT) in CD2-mediated T-cell activation. Following ligation of CD2 on the surface of the Jurkat T-cell line and human purified T cells, LAT was tyrosine phosphorylated and shown to associate in vivo with a number of other tyrosine phosphorylated proteins including PLCgamma-1, Grb-2, and SLP-76. Using Jurkat cell lines deficient in ZAP70/Syk (P116) or LAT (ANJ3) expression, CD2-dependent PLCgamma-1 and SLP-76 tyrosine phosphorylation required expression both of ZAP70 or Syk and of LAT. As predicted, the absence of either LAT or ZAP70/Syk kinases correlated with a defect in the induction of nuclear factor of activated T cells (NFAT) transcriptional activity, activation of the interleukin-2 promoter, and ERK phosphorylation following CD2 stimulation. These data suggest that LAT is an adapter protein important for the regulation of CD2-mediated T-cell activation.

BTI-322, a rat monoclonal IgG2b directed against the CD2 antigen on T cells and natural killer (NK) cells, blocks primary and memory alloantigen proliferative responses in vitro. We have evaluated the pharmacokinetics and safety of BTI-322 during treatment of 20 transplant recipients with steroid-refractory acute graft-versus-host disease (GVHD). Treatment consisted of BTI-322 by intravenous (IV) bolus or 30-minute infusion at approximately 0.1 mg/kg/d for 10 days in addition to continuing high-dose steroids and tacrolimus or cyclosporine. Pharmacokinetic sampling was performed in 10 patients; the t1/2 +/- SE was 9.1 +/- 1.3 hours, the Cmax was 2,549 +/- 291 ng/mL, the Vd was 3.97 +/- 0.95 L, and the Vd/kg was 0. 05 +/- 0.01 L/kg. Ten patients experienced transient dyspnea sometimes accompanied by nausea, vomiting, diarrhea, and tachycardia shortly after the initial bolus dose of drug, but serious drug-related adverse events were not seen during the remainder of the infusions. At the end of treatment (day 11), there were six patients with complete responses and five with a reduction in grade of GVHD for a total response rate of 55% (95% confidence interval [CI], 32% to 77%). Antibodies targeting CD2 may be active in the treatment of acute GVHD, and evaluation of a humanized form of BTI-322 is warranted.

Anti-peptide antibodies against the C-terminal regions of chimeric alpha-amylase, recombinant CD2 and insulin B-chain were obtained by using peptides corresponding to the C-terminal regions as immunogens. These anti-peptide antibodies adsorbed the native proteins, as well as the antigen peptides. The proteins were purified to high purity using the anti-peptide antibodies as affinity ligands. These ligands could discriminate the target proteins having different C-terminal regions. The adsorbed proteins were specifically eluted by the eluents containing the antigen peptides.

In this study, we investigated the efficiency of costimulatory signaling provided by anti-CD2 monoclonal antibodies (mAbs) for the production of type 1 (IL-2 and IFN-gamma) and type 2 (IL-4, IL-5, and IL-10) cytokines by human T cells. We cultured purified human T cells (freshly isolated from blood) with immobilized anti-CD3 mAb, either alone or in combination with anti-CD28 or anti-CD2 mAbs. When compared with the standard costimulatory signal anti-CD28, anti-CD2 mAbs (9-1 plus 9.6) were shown to be more potent costimulators of IL-4 production and to have similar activity for IL-5 production, but to be less potent for costimulation of IL-2, IL-10, and IFN-gamma production. IL-4 production was completely inhibited by cyclosporin A or by blocking IL-2 activity and its receptor. IL-4 and IL-5 were produced by CD45RO+ T cells but not by CD45RA+ T cells, indicating that anti-CD2 in this system costimulated type 2 cytokine production by differentiated memory cells. In the presence of IL-12, the cytokine profile was shifted to high IFN-gamma and IL-10 production and IL-4 and IL-5 production were slightly inhibited. Our data thus suggest that CD2 ligation plays an important role in the upregulation of Th2-like T cell activity (especially IL-4 production), but they also show that this effect is strongly modulated by IL-12, resulting in predominant IL-10 and IFN-gamma production instead., (Copyright 1997 Academic Press.)

Anti-CD3 monoclonal antibodies (MoAbs) and glucocorticoid hormones induce apoptosis in immature thymocytes and peripheral T lymphocytes. This process is inhibited by a number of growth factors, including interleukin-2 (IL-2), IL-3, and IL-4, as well as by triggering of the adhesion molecule CD44, which would indicate that signals generated by membrane receptors can modulate the survival of lymphoid cells. To investigate whether triggering of CD2 may also affect apoptosis in lymphoid cells, we analyzed the effect of stimulation with anti-CD2 MoAbs on T-cell apoptosis induced by two stimuli, anti-CD3 MoAbs and dexamethasone (DEX), using a hybridoma T-cell line and a T-helper cell clone. The results show that CD2 engagement decreased anti-CD3 MoAb-induced apoptosis, but did not influence DEX-induced cell death. Furthermore, the decrease appeared to be related to the expression of Fas/APO-1 (CD95) and Fas-ligand (Fas-L). In fact, we show that CD2 stimulation inhibits apoptosis by preventing the CD3-induced upregulation of Fas and Fas-L in a Fas-dependent experimental system. These data suggest that a costimulatory molecule may control a deletion pathway and may therefore contribute to the regulation of peripheral tolerance.

CD2 mediates interaction between T cells and their cognate partners through its CD58-binding membrane-distal adhesion domain (D1) facilitating T cell receptor (TCR) triggering. A neoepitope defined by anti-CD2R monoclonal antibodies (mAbs) has suggested structural alteration within the CD2 ectodomain during T cell activation. Here, we map CD2R to the flexible CD2 linker region between D1 and the membrane-proximal extracellular domain (D2) and show that exposure of this conformational site is independent of temperature and metabolic energy. Co-ligation of CD2 and CD58 molecules on opposing cells within a conjugate pair induces CD2R and redistributes CD2 to the region of cell-cell contact. These CD2R+ molecules, in contrast to the CD2R-molecules, are tightly clustered on the T cell surface. Hence, a ligand-mediated increase in the D1-D2 interdomain angle apparently exposes CD2R, facilitates packing of CD2 molecules in a clustered array and is linked to CD2-mediated adhesion and activation events. Conformational alteration of this type may be generally important in ordered lattice formation involving surface receptors.

The induction of monocyte IL-1 mRNA during T cell activation requires that monocytes receive contact-dependent signals from activated T cells. Furthermore, the ability of T cells to induce IL-1 beta mRNA is not constitutive but rather is rapidly acquired (< or = 30 min) following activation via mechanisms that do not require protein synthesis. The goal of these studies is to identify the T cell signal(s) that mediates the cell contact-dependent induction of monocyte IL-1 beta mRNA. The induction of IL-1 beta mRNA during anti-CD3 mitogenesis was significantly inhibited by anti-CD2 mAb, whereas mAb against CD11a, CD18, CD69, or CD5 molecules had no effect. The inhibition of IL-1 beta mRNA induction by anti-CD2 mAb was restricted to only those mAb that block CD2/CD58(LFA-3) interactions. Furthermore, anti-CD2 blocked the induction of monocyte IL-1 beta mRNA by T cells that were preactivated using either immobilized anti-CD3 or anti-T11(2) plus anti-T11(3) mAb, thereby indicating that the inhibition of IL-1 beta mRNA was not due to negative signaling effects exerted on the T cell by anti-CD2. Finally, although anti-CD69 mAb had no effect on IL-1 beta mRNA induction, it inhibited the generation of soluble IL-1 beta. The combination of anti-CD69 and anti-CD2 mAb exhibited greater inhibition of secreted IL-1 beta than either antibody alone. These results indicate that CD2 is required for T cell induction of IL-1 beta mRNA through interaction with LFA-3 on the monocyte and that the generation of soluble IL-1 beta is regulated by CD69.

A sero-epidemiologic correlation study on immune parameters which would correlate with the frequency of common colds (FCC) had been conducted in 1992. There, an inverse relationship between circulating adhesion molecules CD54 and CD58 and FCC was found. Eighteen months later we performed an analogous assessment in order to verify the previous findings and to carry out additional experiments including in vitro proliferative responses of T cells and their production of various cytokines (IFN-gamma, IL-2, IL-6 and IL-10). The additional examinations showed that individuals with frequent common colds exert a higher T cell proliferation and higher production of cytokines than persons which experience never or few common cold infections. These findings could be confirmed statistically. Taken together, the results suggest consistently in individuals with frequent common colds an association with low serum levels of the immunosuppressive soluble adhesion molecules sCD54 and sCD58, high proliferation of unstimulated and stimulated T cells and secretion of higher concentrations of cytokines (IFN-gamma, IL-2, IL-6 and IL-10) into the cell culture supernatants.

Monoclonal antibodies recognizing CD27, a member of the nerve growth factor receptor family, have been observed to enhance or inhibit PHA- or CD3 mAb-stimulated T cell proliferation. In this study, we investigate the effects of CD27 stimulation on the proliferation and cytokine production of T cells stimulated simultaneously through CD3, CD2, or CD28. Here we report that simultaneous crosslinking of CD27 plus CD28 results in T cell proliferation and in the production of IL-2, IL-4, IL-10, and IFN-gamma. CD27 plus CD28 stimulation thus introduces a novel Ag-independent pathway of T cell activation. We further show that all major T cell subsets (CD4+, CD8+, CD4+CD45RA+, or CD4+CD45RO+ T cells) respond to CD27 plus CD28-mediated costimulation. Synergistic effects on T cell stimulation are also found when CD27 is crosslinked on cells stimulated simultaneously through CD3 or CD2. In further experiments we show that crosslinking of CD27 elevates cytoplasmic free Ca2+ levels. Finally, both the CD3 plus CD27 and the CD28 plus CD27-stimulated T cell proliferation is sensitive to inhibition by CsA. Taken together, these data emphasize the importance of CD27 stimulation in the context of simultaneously received signals through CD3, CD2 or, most importantly, through CD28. Furthermore, signaling through CD27 appears to involve Ca(2+)-dependent mechanisms sensitive to CsA.

Mitogenic pairs of CD2 mAb typically transduce activation/proliferation signals within T cells. However, complementary signal(s) provided by accessory cells are required to induce T cell proliferation. We show here that a particular combination of three CD2 mAb, D66 + GT2 + T11.1, leads to the proliferation of highly purified human T lymphocytes, without other complementary signal(s). The CD2 triplets was able to induce CD4+ and, to a lesser extent, CD8+ cells to proliferate. Interestingly, the so-called "naive" T cells (CD45RA+) were strongly stimulated, but more immature cells, such as thymocytes, were not. The proliferative response induced by the CD2 triplet was entirely mediated by the IL-2 autocrine pathway, as shown by the complete inhibition with anti-IL2 Ab. T cells stimulated with the CD2 triplet were also able to secrete TNF alpha. We found no evidence for an unusual secretion of cytokines that might explain the lack of requirement of complementary signal(s). As high as it was, the proliferation induced by the CD2 mAb triplet could be further increased by the addition of IL-1, and this proliferative fraction could be inhibited by antibodies against TNF alpha. The CD2 mAb triplet increased [Ca2+]i, while mitogenic CD2 mAb pairs needed the presence of a cross-linking agent. Thus, our data show that T cells can be activated to fully proliferate by this particular CD2 pathway, in the absence of accessory signal(s).

The use of transgenic technologies in the functional evaluation of the contributions of costimulatory pathways to T-cell activation in vivo has recently undergone a rapid expansion. During the past two years, mice deficient in costimulatory molecules and their receptors have been generated. These mice have revealed novel and critical in vivo functions of costimulatory pathways and have provided valuable models in which to test therapeutic strategies involving costimulatory pathway blockade. Transgenic mice constitutively expressing costimulatory molecules have provided insights into their role in peripheral tolerance.

Patients who have undergone allogeneic bone marrow transplantation (allo-BMT) are susceptible to a variety of opportunistic infectious complications in the months to years after engraftment. Impaired in vitro T-cell functions have been documented in these patients, and these T-cell dysfunctions contribute to the prolonged immune deficiency after allo-BMT. In the present study, we examined the expression of CD26 as well as the reconstitution of CD26-mediated T-cell costimulation via the CD3 and CD2 pathways at various times in patients aged greater than 18 years after CD6-positive, T-cell depleted allo-BMT. We found that the percentage of CD26- and CD3-positive cells, as well as the levels of expression of both antigens, was lower than in normal controls during the first 4 months after CD6-depleted allo-BMT. Subsequently, the amount of lymphocytes expressing CD3 and CD26 and the quantitative surface expression of CD3 and CD26 were not significantly different in patients and normal controls. Functional studies showed that CD26-mediated T-cell proliferation via the CD3 pathway was considerably improved and almost reached normal levels by 1 year, whereas recovery of CD26-mediated T-cell proliferation via the CD2 pathway was delayed for at least 2 years after CD6-depleted allo-BMT. As CD26 involvement in the regulation of human thymocyte activation is restricted preferentially to the CD3 pathway--unlike its involvement with both CD3 and CD2 pathways of peripheral T cells--our results suggest that the different effects of CD26-mediated costimulation via the CD3 and CD2 pathways after CD6-depleted allo-BMT may be a reflection of peripheral T-cell immaturity in those individuals, similar to that seen in mature medullary thymocytes or cord T lymphocytes.

Murine monoclonal antibodies, HB88A, B29A and DH59B separately identify the CD2 T lymphocyte molecule, a unique pan-B lymphocyte surface marker and a pan-granulocyte/monocyte surface molecule, respectively, in the horse. Specificity was shown by two-color immunofluorescent flow cytometry and immunofluorescent microscopy. MAb HB88A reacted with a 52 kDa pan-T lymphocyte molecule present on 75% +/- 7 of peripheral blood lymphocytes (PBL) (n = 15 horses). It also reacted with lymphocytes restricted to T lymphocyte dependent areas of lymph node and spleen. Specificity of mAb HB88A to CD2 was demonstrated by its reactivity to COS7 cells which expressed a transfected 1.5 kb equine lymphocyte c-DNA clone having 77.5% overall sequence homology with human CD2 c-DNA. MAb B29A reacted with a pan-B lymphocyte specific cell surface complex, 143, 72, 50, 40, 27 and 14.5 kDa, present on 19% +/- 7 of PBL (n = 15 horses). This complex has not been described in the horse or other species. MAb DH59B reacted with a 96 kDa pan-granulocyte/monocyte specific surface protein and identified macrophages and Kupffer cells in equine tissue sections. Together these mAbs can be used to identify and quantitate the major constituents of equine leukocytes.

Specific adhesion molecules stabilize the binding between lymphocytes and antigen bearing cells; this intercellular adhesion is vital to both the affector and effector phases of an immune response. It is not known whether adhesion molecules and their counter-receptors can form the cross-species interactions that will facilitate human T cell recognition of xenogeneic porcine target cells. In this report it is demonstrated that a higher proportion of mitogen-activated than of resting human lymphocytes adhere to cultured porcine renal epithelial cells. Furthermore, antibody blocking experiments demonstrated that at least part of this cell-cell binding is stabilized by the human adhesion molecules LFA-1 (lymphocyte function-associated antigen-1) and the alpha 4-containing integrins. It is possible that this capacity for cross-species adhesion will play a role during the cell-mediated rejection of clinical porcine xenografts.