SEARCH · PubMed Health

Results for “CD3 Complex”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 613 records · Page 34Linked to original sources

PubMed2005

The recognition pattern of gammadelta T cells.

The main function of immune system is to recognize and respond to foreign antigens. During the course of evolution, the body has successfully developed four kinds of mechanisms to recognize antigens, including pattern recognition mediated by macrophages, missing-self and induced-self recognition for NK cells, antigen specific recognition for alphabeta T cells and B cells and "broad-spectrum specific" recognition for gammadelta T cells. The three formers have made great progress these years. However, details of antigen recognition by gammadelta T cells are still mysterious. Gammadelta T cells, a class of T cells only existing in primates, differ from alphabeta T cells in TCR diversity, the structure of TCR-CD3 complex, the tissue distribution, the antigens that they recognize and the way involved in recognition. Here, we shed light on the recognition mechanism of gammadelta T cells against several known antigens and discuss the possible response pattern along the research historical process. We put forward a recognition hypothesis for gammadelta TCR that is conformational recognition based on germline encoded recognition. The key germline encoded amino acids dominate the "putative binding box" and are responsible for recognition. Meanwhile, after gammadelta T cells are activated, several other molecules such as CD69, CD16, 2B4, NKG2D also participate in inducing cytotoxicity of activated gammadelta T cells. Obviously, the illustration of recognition mechanism for gammadelta T cells will help to comprehensively understand the whole immune system and design the higher effective multi-epitope vaccines for tumor and infection immunity.

Animals↗

PubMed1999

Gene therapy approaches to HIV-infection: immunological strategies: use of T bodies and universal receptors to redirect cytolytic T-cells.

Combined regimens of classical antiviral treatments have not, until now, lead to the eradication of HIV-1. A specific anti-HIV immune response may have to be boosted or transferred to patients after suppression of viral replication, in order to eradicate residual infected cells from their sanctuaries. Cytotoxic T cells engineered to express recombinant chimeric receptors can be redirected against HIV-infected cells and could represent the basis of a new type of immunotherapy. Several HIV epitopes have been targeted successfully in vitro. Two types of binding domains (antibody fragments, CD4) fused with various signal transducing units (zeta chain of the CD3 complex, Fc epsilon RI gamma chain) have been tested for their ability to redirect effector cells to HIV infected lymphocytes. CD4-zeta-expressing myeloid and natural killer cells conferred SCID mice protection against challenge with tumor cells expressing HIV-env. Finally, the safety of the adoptive transfer of syngeneic CD4-zeta -modified T cells in HIV-infected individuals is currently under evaluation.

Animals↗

PubMed1994

Expression of human recombination activating genes (RAG-1 and RAG-2) in lymphoma.

Two recently discovered genes, the recombination activating genes 1 and 2 (RAG-1 and RAG-2), are necessary to perform variable (V), diversity (D), and joining (J) recombination. They synergistically activate VDJ recombination to generate immunocompetent lymphocytes. Disruption of either gene results in a maturation arrest at a very early B and T cell progenitor stage. Expression and downregulation of RAG's are closely associated with interleukin 7, sIgM and TCR-CD3 complex, respectively. Assessment of RAG mRNA expression is a valuable marker in identifying the genotypic maturation status of leukemias and lymphomas. Persistent RAG expression in otherwise mature lymphoid proliferations may explain puzzling biological and clinical observations such as multiple rearrangements in lymphomas with a mature phenotype. Lack of RAG expression in Hodgkin's disease with abundant Reed-Sternberg cells is consistent with a mature phenotype of the latter. Availability of a anti-RAG-1 monoclonal antibody in the near future will facilitate RAG analysis of lymphomas.

Animals↗

PubMed2000

CD152 ligation by CD80 on T cells is required for the induction of unresponsiveness by costimulation-deficient antigen presentation.

Two apparently contradictory observations have been made concerning peripheral T cell tolerance; costimulation-deficient Ag presentation leads to unresponsiveness, and CTLA4 (CD152) ligation is required for unresponsiveness to be induced. This issue was addressed using a CD80- CD86low B cell line to present Ag to DO.11.10 naive CD4+ T cells. Proliferation was substantially enhanced by anti-CD80 or anti-CD152, but was inhibited by anti-CD86. Furthermore, anti-CD80 partially, and anti-CD152 totally protected cloned DO.11.10 T cells from the induction of unresponsiveness following culture with peptide and Chinese hamster ovary H2-Ad+ CD80- CD86- cells. Fab of anti-CD80 caused similar enhancement, and coimmobilized anti-CD80 failed to costimulate the anti-CD3 response of purified T cells, indicating that direct signaling by anti-CD80 was not responsible for these effects. The possibility that anti-CD80 liberated CD28 molecules that were sequestered by the T cell-expressed CD80, enabling them to coaggregate with TCR:CD3 complexes was excluded by finding that anti-CD80 and anti-CD152 individually caused maximal enhancement, rather than having additive effects. These data suggest that T cell-expressed CD80 has a regulatory function and plays a key role in the induction of unresponsiveness due to costimulation-deficient Ag presentation by the ligation of CD152 on neighboring, or even the same, T cell.

Abatacept↗

PubMed2001

Integrin functions play a key role in the differentiation of thymocytes in vivo.

T cells express a variety of surface proteins as they develop to maturity in the thymus. In addition to the TCR-CD3 complex and the two major coreceptors, CD4 and CD8, other surface proteins expressed include receptors for cytokines, growth factors, counterreceptors, and extracellular matrix molecules. To determine the role of integrin adhesion receptors in T cell development, we have expressed a trans-dominant inhibitor of integrin function in the thymus. This inhibitor leads to a block of adhesion to fibronectin due to reduced activation of integrin receptors. This reduced adhesion leads to a partial block in differentiation from CD4-CD8- cells to CD4+CD8+ cells, after the CD25+ stage, suggesting that integrins are important during Lck-mediated differentiation. Furthermore, the overall production of CD4+ cells is reduced compared with that of CD8+ cells without changes in negative selection, suggesting that integrins may be involved in the determination of the fate of the cell as well. These results demonstrate that integrin receptor function is required for proper thymocyte development in vivo.

Animals↗

PubMed2005

The low affinity Fc receptor for IgG functions as an effective cytolytic receptor for self-specific CD8 T cells.

We have recently described a population of self-Ag-specific murine CD8(+) T cells with a memory phenotype that use receptors of both the adaptive and innate immune systems in the detection of transformed and infected cells. In this study we show that upon activation with IL-2 with or without Ag, between 10 and 20% of the activated self-specific CD8(+) T cells express the low affinity FcR for IgG. By contrast, all IL-2-activated NK cells express high levels of this FcR. The FcR comprises the FcgammaRIIIalpha and FcRgamma subunits. However, the FcRgamma subunit also associates with the CD3 complex, and this association probably contributes to the low expression of FcR in activated cells. Although the FcR is expressed at a low level on activated self-specific CD8(+) T cells, it functions very efficiently as a cytolytic receptor in ADCC. FcR-dependent killing occurred in the absence of TCR stimulation, but could be augmented by concurrent stimulation of the TCR. In addition to mediating ADCC, engagement of the FcR on self-specific CD8(+) T cells results in the production of both IFN-gamma and TNF-alpha. This is the first report of an activating FcR on self-specific murine CD8(+)alphabeta TCR(+) T cells and establishes the importance of innate immune system receptors in the function of these self-specific CD8(+) T cells.

Animals↗

PubMed1998

[Antigen-recognition mechanism of T cells].

The antigen-recognition mechanism of T cells was reviewed from the standpoint of MHC-restriction. T cells recognize antigens presented by antigen-presenting cells in a MHC-restricted manner. CD4+ helper T cells recognize antigens with the context of MHC class II molecules, and CD8+ cytotoxic T cells recognize antigens with MHC class I molecules. The MHC class I molecule is composed of alpha-chain and beta 2-microglobulin, and MHC class II molecule is composed of alpha-chain and beta-chain. The T cell antigen receptor is composed of alpha-chain and beta-chain, or gamma-chain and delta-chain, and CD3 complex. Antigens are processed and presented by antigen-presenting cells to T cells in the context of MHC molecules. Furthermore, costimulatory factors such as adhesion molecules and cytokines are required for the full activation of T cells. The biological significance of the T cell antigen recognition mechanism is discussed from the standpoint of clinical application.

Antigen-Presenting Cells↗

PubMed1999

Direct effects on antigen-presenting cells and T lymphocytes explain the adjuvanticity of a nontoxic cholera toxin mutant.

The present study has elucidated two distinct mechanisms that may explain how a mutant of cholera toxin (mCT), E112K, retains adjuvant effects though it lacks ADP-ribosyltransferase activity and associated toxicity. In the first mechanism, we show that mCT E112K, like native cholera toxin (nCT), enhances B7-2 expression, but, to some extent, also enhances B7-1 on Peyer's patch B cells and macrophages. Cocultivation of CD4+ T cells with E112K- or nCT-treated B cells and macrophages in the presence of anti-CD3 stimulation resulted in the induction of T cell-proliferative responses. Further, the responses were blocked by mAbs to B7-1 and/or B7-2; however, the effect of anti-B7-1 was minimal. In the second mechanism, addition of mCT E112K or nCT to anti-CD3 mAb-stimulated Peyer's patch CD4+ T cells inhibited proliferative responses, while recombinant CT-B subunit (rCT-B) did not. Analysis of cytokine responses showed that both mCT E112K and nCT preferentially inhibited IFN-gamma production. Interestingly, however, nCT, but not mCT E112K, induced apoptosis in CD4+ T cells activated via the TCR-CD3 complex. These results indicate that CT uses at least two pathways for inhibition of Th1 responses and that, while nCT induces cAMP accumulation that in turn leads to apoptosis in Th1-type cells, mCT E112K, which lacks ADP-ribosyltransferase activity, inhibits IFN-gamma synthesis by a separate mechanism. Thus, mCT E112K, like nCT, induces adjuvant responses via up-regulation of mainly B7-2 on APCs and through preferential inhibition of Th1-type CD4+ T cell responses in the absence of ADP-ribosyltransferase activity.

Adjuvants, Immunologic↗

PubMed2000

Signaling via LAT (linker for T-cell activation) and Syk/ZAP70 is required for ERK activation and NFAT transcriptional activation following CD2 stimulation.

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.

Adaptor Proteins, Signal Transducing↗

PubMed2001

A novel leucine-rich repeat protein (LRR-1): potential involvement in 4-1BB-mediated signal transduction.

4-1BB, a member of the tumor necrosis factor receptor (TNFR) superfamily, is induced on CD4+ and CD8+ T cells upon engagement of the T cell receptor (TCR)/ CD3 complex with the antigen bound to MHC. 4-1BB plays an important role in transmitting costimulatory signal during T cell activation. However, 4-1BB-mediatded signal transduction pathways have remained elusive. We conducted the yeast two-hybrid screening to identify intracellular signaling molecules that associate with 4-1BB. A novel leucine-rich repeat (LRR)-containing protein, herein named LRR-1, was found to specifically interact with the cytoplasmic domain of 4-1BB. Overexpression of LRR-1 suppressed the activation of NF-KB induced by 4-1BB or TNF receptor-associated factor (TRAF) 2. In addition, LRR-1 down-regulated JNK1 activity was induced by 4-1BB. These results indicate that LRR-1 negatively regulates the 4-1BB-mediated signaling cascades which result in the activation of NF-kappaB and JNK1.

Amino Acid Sequence↗

PubMed2000

T Cell Functional Disturbances in Patients with Pulmonary Tuberculosis.

The investigations of 38 patients with pulmonary tuberculosis (PT) revealed combined T cell and monocyte functional disturbances. Indeed, the percentages of CD4(+) and CD8(+) T lymphocytes, proliferative response and IL-2 production, as well as the percentages of HLA DR(+) monocytes and IL-1beta production were significantly decreased in PT patients as compared with normal individuals. Herewith the absolute T lymphocyte number did not undergo the pronounced changes. The decrease of T cell proliferative response was not mediated through immunosuppressive action of monocytes or T lymphocytes since removing of "adherent" cells from patient's peripheral blood mononuclear cells (PBMC) or pretreatment of PBMC with indomethacin and cyclophosphan failed to recover mitogenic reactivity in vitro. The patient's sera also did not significantly influence on PBMC proliferation. The decrease of IL-2 production and the stimulation of T cell proliferative response via TcR-CD3 complex, i.e. through the classic pathway of activation, indicated the anergy of T lymphocyte in tuberculosis patients. Furthermore, T lymphocytes were characterized by enhanced apoptosis. It should be noted, that patient's sera (especially in the patients with an initially high apoptosis) promoted significant anti-apoptotic activity. It is likely that this mechanism may be an explanation, why absolute T lymphopenia is absent during tuberculosis infection. Our findings suggest, that T lymphocyte dysfunctions in patients with PT are caused by impairments of T cell activation process, which lead to predominance of "negative" response (induction anergy, apoptosis) and to a lesser degree connected with direct suppressive mechanisms mediated by monocytes, T lymphocytes or serum factors.

Journal Article↗

PubMed1992

In vivo induced allo-reactive natural killer cells.

We have previously shown that rat allo-selective cells of the CD2+CD5- phenotype were generated in Brown Norway (BN) rats after immunization with allogeneic Wistar/Furth (WF) cells, whereas immunization with semi-allogeneic F1 (WF/BN) cells generated CD2+CD5+ effector T cells. We now report that the allo-selective CD2+CD5- lymphocytes lacked expression of intact CD3 complexes and expressed NKR-P1 molecules although lower as compared to classical NK cells, implicating that these lymphocytes constitute a subset of NK cells. The CD5+ T cells were not cytolytically active in BN rats immunized with WF cells indicating an intersubset regulation with mutually exclusive activation of either allo-selective T cells or allo-selective NK cells. Cold target inhibition showed that lysis of both allogeneic target cells and NK-sensitive target cells was mediated by the same NKR-P1 intermediate effector cells. These NK cells lysed WF but not allogeneic Fischer 344 or autologous BN target cells, indicating selective recognition of an allogeneic determinant. Semiallogeneic F1 (WF/BN) target cells were not lysed. Furthermore, target cells from F1 (WF/BN) x WF back-cross hybrids lacking expression of RT1n (self-MHC class I) were susceptible to lysis, whereas back-cross hybrids expressing RT1n were protected from lysis, indicating that self-MHC molecules conferred protection from lysis. These findings implicate the existence of NKR-P1intermediate and NKR-P1high NK cell subsets with different regulation and function in vivo.

Animals↗

PubMed1992

[Effect of indirect endolymphatic antibiotic therapy on clinical and immunological indicators in patients with erysipelas of the lower extremities].

Two groups of patients with erysipelas of the lower extremities underwent indirect endolymphatic therapy with bicillin-3 (58 patients) and routine penicillin therapy (79 patients). Comparative clinicoimmunological examinations in the two groups revealed that lymphotropic administration of the antibiotic had a more favourable effect on the disease process, as evidenced by more rapid reverse time courses of erysipelas clinical signs, less frequent incidence of early relapses and normalization of the majority of immunological parameters by the end of the treatment. For estimation of the anti-recurrence efficacy of the antibiotic therapy in the patients with erysipelas, it was recommended to use a specific scale based on the principles of the Wald successive alternative analysis.

Adult↗

PubMed1992

Evidence for a role for T cell receptors (TCR) in the effector phase of acute bone marrow graft rejection. TCR V beta 5 transgenic mice lack effector cells able to cause graft rejection.

Lethally irradiated mice reject within 24 h certain marrow grafts, a phenomenon called either allogeneic or hybrid resistance. The cells responsible for this rejection (NK1+ CD3+ cells (TNK) express Ag of NK cells as well as the TCR-associated CD3 complex. This raises the question whether TCR participate in the function of these cells during graft rejection. By using flow cytometry it is shown that the majority of TNK cells expresses the TCR-alpha/beta chains and by using adoptive cell transfer assays evidence is presented that it is the TCR-alpha/beta expressing cells that cause rejection. To explore whether any particular TCR chains have to be expressed on these cells, C57L mice were assayed and found to be responders suggesting that the V beta chains deleted in these mice are not obligatory. However, introduction of a specific TCR V beta 5 chain into C57BL/6 mice as a transgene leads to inability to transfer resistance. TNK cells of V beta 5 transgenic mice express the introduced gene suggesting that it is the transgenic TCR that is responsible for the lack of function. In assessing T cell functions in V beta 5 transgenic mice it is shown that although these mice generate CTL specific for H-2d targets there is a deficiency to recognize H-2Dd, i.e., of determinants presumed to be recognized in the acute rejection mechanism. Thus TNK cells and CTL share the inability to recognize H-2Dd epitopes due to expression of the V beta 5 transgene. The notion that TCR on TNK cells play a role in the acute rejection process makes it necessary to postulate a receptor selection mechanism for these cells.

Acute Disease↗

PubMed1992

Molecular cloning and expression pattern of a human gene homologous to the murine mb-1 gene.

The mouse mb-1 gene was originally identified based on its restricted expression in B lineage cells. Predicted structural homology with the gamma chain of the CD3 complex on T cells led to the suggestion that the MB-1 protein might associate with surface Ig(sIg) on B cells and be involved in signal transduction. Other studies identified at least two proteins that are noncovalently associated with sIgM, one of which has recently been shown to be the product of the mb-1 gene. To identify genes specifically expressed in normal human B cells we constructed a B minus T lymphocyte subtraction library and isolated a cDNA clone highly homologous to murine mb-1 (m-mb-1). A full-length cDNA was subsequently isolated and found to encode a membrane glycoprotein of 226 amino acids. It included a leader sequence (32 amino acids), an extracytoplasmic domain (111 amino acids) containing six potential N-glycosylation sites and three cysteine residues for potential inter- or intrachain disulfide linkages, a transmembrane domain (22 amino acids), and an intracytoplasmic domain (61 amino acids). The amino acid sequence homology between human and mouse mb-1 was especially striking (approximately 92%) in the intracytoplasmic, transmembrane, and membrane-proximal extracellular domains but was less marked (approximately 42%) in the remaining extracytoplasmic portion. Interestingly, part of the 3'-untranslated region was also highly conserved between species, suggesting an important role for this region in the regulation of mb-1 expression. The human mb-1 (h-mb-1) cDNA hybridized with a mRNA species of approximately 1.2 kb on Northern blots. Similar to m-mb-1, the h-mb-1 transcripts could be detected in pre-B cell lines and fetal bone marrow, in normal, mitogen activated- and transformed B cells but not in myeloma plasma cells. h-mb-1 was not expressed in peripheral T cells nor by cells of other hemopoietic lineages or in brain, heart, muscle, lung, and kidney. Surprisingly, however, low levels of h-mb-1 transcripts were detectable in two early T lineage cell lines and in the fetal thymus. This suggests that mb-1 may have other functions in addition to its role in signal transduction in B lineage cells.

Amino Acid Sequence↗

PubMed1996

Regulation of the anti-allograft response by targeting the CD2 antigen: a potential strategy for the creation of transplant tolerance.

Activated T cells playa central role in the rejection of histoincompatible organ allografts. Studies of trans- membrane signaling requirements ofT cells, by identifying molecular and cellular mechanisms ofT-cell activation, can lead to rational therapeutic strategies for the regulation of the anti-allograft response. A clear consensus exists that the primary signal for T-cell activation is generated as a consequence of the in- teractions among the T-cell receptor for antigen (TCR)I cluster designation 3 (CD3) complex and the antigenic peptide presented in the context of major histocompatibility complex (MHC) proteins expressed on the sur- face of the antigen-presenting cells (APCs). '-7 The TCR/CD3-dependent signaling is necessary but insufficient in itself to fully activate normal human primary (quiescent) T cells, and additional costimulatory signals are required for full activatiori.

Journal Article↗

PubMed2006

[Antitumor and chemopreventive activity of lactoferrin].

Lactoferrin, an evolutionarily old protein of the transferrin family, is among the proteins constituting the system of innate immunity; its action, however, also extends to the regulation of acquired immunity and other immunological phenomena. The actions of LF, confirmed in numerous in vitro and in vivo models, include participation in iron homeostasis, immunoregulatory properties, anti-inflammatory, anti-tumor, and analgesic actions, regulation of bone metabolism, participation in embryonic development, reproductive functions, and others. LF plays an important role in the normal development of a newborn. The anti-tumor properties of LF were discovered about a decade ago and have been confirmed in many laboratory, preclinical, and clinical studies. The immunomodulatory properties of LF play a major role in its anti-tumor actions. Such actions of LF appeared particularly effective in cancer patients with impaired immunity. The growth of tumors is facilitated by low expressions of MHC and co-stimulatory antigens on tumor cells and the induction of suppressor cells and other inhibitory products by tumors. Enhancement of an anti-tumor immunological response may, therefore, restrict tumor growth. Studies showed that LF elevates the number and increases the activity of T and B lymphocytes and NK cells, stimulates the release of a number of cytokines (IL-1, -6, -8, -18, IFN-gamma, TNF alpha), increases phagocytic activity and cytotoxicity of monocytes/macrophages, accelerates the maturation of T and B cells, and elevates the expression of several types of cellular receptors, such as CD4, zeta chain of the CD3 complex, LFA-1, CD11, ICAM-1, and selectin P. Apart from its immunomodulatory properties, LF exhibits direct anti-tumor actions, such as lytic, pro-apoptotic, anti-proliferative, anti-angiogenic, anti-oxidant activity and the chelation of iron ions. LF also possesses chemo-preventive properties, regulates the activity of phase I and II enzymes participating in the activation and detoxification of carcinogens, and regulates the composition of the intestinal microflora. In this way it prevents the generation of tumors and their development at early stages of carcinogenesis.

Analgesics↗

PubMed2006

Immunohistochemical typing of non-Hodgkin's lymphoma-comparing working formulation and WHO classification.

The recent WHO classification of non-Hodgkin's lymphoma is based on the morphology and immunohistochemical expression of the lymphoma cells and to a lesser extent, on the molecular and cytogenetic findings. Fifty-three cases of non-Hodgkin's lymphoma were included in the study. Of these, seven cases were primary extra nodal lymphomas. Twenty two patients had peripheral blood and/or bone marrow involvement. A detailed morphological assessment was done and classified using the International working formulation. The two most common types encountered were diffuse large cell lymphoma and small lymphocytic lymphoma. Immunohistochemistry was done using labeled streptavidin-biotin peroxidase complex with CD3, CD20, CD15, CD30, CD 45 (leukocyte common antigen), Cyclin D1, EMA (epithelial membrane antigen). 38 cases (72%) showed B cell expression and 12 cases (22.5%) showed T cell expression. Three cases did not express either marker. B-cell diffuse large cell lymphoma (26%) was found to be the predominant B cell non-Hodgkin's lymphoma. The commonest T-cell lymphoma was T lymphoblastic lymphoma (67%) followed by peripheral T cell angioimmunoblastic lymphoma (25%). Immunohistochemistry is a useful and necessary diagnostic modality and helps subdivide prognostically different types of non-Hodgkin's lymphoma.

Adolescent↗