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At least 1,063 records · Page 59Linked to original sources
PubMed1999

Is there any relationship between interleukin-6/interleukin-6 receptor modulation and endogenous interleukin-6 release in metastatic malignant melanoma patients treated by biochemotherapy?

During recent years it has become clear that the production of most cytokines could play an important role in malignancies. We previously demonstrated that a high endogenous interleukin-6 (IL-6) level is significantly correlated with a high tumour burden and resistance to biochemotherapy in metastatic malignant melanoma patients. However, little is known about the origin of IL-6 and the pattern of IL-6 receptor (IL-6R) expression. In this report, we studied the expression of IL-6R and intracellular IL-6 using flow cytometry in tumour cells provided by fine-needle aspiration of lymph nodes and palpable metastatic lesions from 14 patients refractory to biochemotherapy and six responder patients. Moreover, we established the relationship between these parameters and the serum IL-6 level. Our results demonstrated that, following treatment, the percentage of HMB45-positive (HMB45+) cells expressing functional IL-6R, intracellular IL-6 or both IL-6R and IL-6 significantly decreased in patients refractory to biochemotherapy. In contrast, in responder patients the percentage of HMB45+ cells expressing IL-6R increased and those expressing IL-6 remained stable. Regarding the serum IL-6 level, an 11-fold increase was observed in the patients refractory to biochemotherapy, but only a 1.8-fold increase in the responder patients. In conclusion, in metastatic malignant melanoma patients with a poor prognosis, the endogenous production of IL-6 is concomitant with a decrease in functional IL-6R and intracellular IL-6 expression, suggesting the involvement of an IL-6/IL-6R complex.

Adult↗
PubMed2001

Immunological evaluation of patients with beta-thalassemia major.

Abnormalities in the immune system and zinc homeostasis in patients with beta-thalassemia major (TM) have been reported. Since zinc ion is essential for the efficiency of the immune system and is required to induce biological activity to thymulin (Zn-FTS), a biochemically defined thymic hormone, we investigated the plasma levels of zinc and both active thymulin (Zn-FTS) and total zinc saturable thymulin (Zn-FTS+FTS) in 18 patients with TM aged between 2 and 31 years and 22 normal controls of the same age. Inhibitory molecules anti-thymulin and the distribution of lymphocyte subsets were also analyzed. Patients with TM presented significantly lowered plasma zinc and thymulin levels when compared to normal subjects. The significant enhancement of the active form of the hormone after zinc addition in vitro suggests that low thymulin values found in TM are due not to a thymic failure in synthesizing and secreting the thymic hormone, but a defect in zinc saturation of the hormone. An impairment of cell subset distribution was also demonstrated. This study shows that zinc and thymulin deficiency contribute to the complex mechanisms underlying immune dysfunction in TM.

Adolescent↗
PubMed1994

Augmentation of NK cell activity and proliferation in cultured lymphocytes of leukemic patients by monoclonal antibodies CD3 and interleukin-2.

The aim of the present study was to induce NK cell activity in peripheral mononuclear cells (PMNC) of normal individuals or of leukemic patients. For this purpose, monoclonal antibodies (mAbs) anti-CD3 (MEM 57, OKT 3 and MEM 92), anti-CD59 (MEM 43) and anti-CD43 (MEM 59) were tested. MEM 43, MEM 59, MEM 57 and OKT 3 stimulated markedly the NK activity in fresh isolated PMNC of normal individuals, whereas the cytotoxicity in 3-day cultivated PMNC was enhanced only by MEM 57 and OKT 3. In comparison to interleukin-2 (IL-2), MEM 57 and OKT 3 induced less PMNC cytotoxicity but more cell proliferation. MEM 92 (anti-CD3, IgM) compared to MEM 57 or OKT 3 (anti-CD3, IgG) did not show any effect on both reactions mentioned above. PMNC of untreated leukemic patients exerted very negligible NK cell activity. Following 3-day culture of leukemic PMNC with OKT 3 or IL-2 the anti-K 562 cytotoxicity was markedly enhanced. In some cases the stimulating effect was more pronounced by IL-2, in others by OKT 3. Nevertheless, the best effect was gained in 7 out of 12 patients using a combination of IL-2 and OKT 3. On the other hand, OKT 3 did not synergize with IL-2 in normal PMNC culture.

Antibodies, Monoclonal↗
PubMed1993

Simultaneous involvement of all six predicted antigen binding loops of the T cell receptor in recognition of the MHC/antigenic peptide complex.

The TCR is predicted to resemble the Fab fragment of an Ig molecule and by analogy to possess six Ag binding loops that contact MHC proteins bound with antigenic peptides. We have identified residues in the predicted Ag binding loops (beta 1, beta 2, and beta 3) on a TCR beta-chain that are important in the recognition of the MHC/antigenic peptide complex. Using site-directed mutagenesis, we altered the residues forming the predicted Ag binding site on the beta-chain expressed by the T lymphocyte clone D5, which specifically recognizes p-azobenzenearsonate-conjugated peptides presented by the class II MHC molecule I-Ad. Amino acid substitution of individual residues in each loop affected Ag recognition, demonstrating that all three putative Ag binding loops of the D5 TCR beta-chain are important in interaction with I-Ad/arsonate-conjugated Ag. Taken together with our previous work on the D5 TCR alpha-chain (Nalefski et al., J. Exp. Med. 175:1553), these results suggest that all six Ag binding loops of the D5 TCR alpha- and beta-chains interact simultaneously with the MHC/peptide complex. Consequently, the area of interaction between the TCR and the MHC/antigenic peptide complex is predicted to be extensive.

Amino Acid Sequence↗
PubMed1997

Itk, a T cell-specific tyrosine kinase, is required for CD2-mediated interleukin-2 promoter activation in the human T cell line Jurkat.

We investigated the functional role of Itk, a member of the cytoplasmic tyrosine kinase Tec family, in T cell activation. Stimulation of either CD2 or T cell receptor (TCR)/CD3 on Tcells by monoclonal antibody-mediated cross-linking induced tyrosine phosphorylation of Itk, which was maximal as early as 1 min after stimulation. The tyrosine kinase activity in the anti-Itk immunoprecipitate was significantly activated upon these stimulations. Interleukin-2 (IL-2) promoter activity stimulated by cross-linking of CD2, TCR/CD3, and CD28 with antibodies was significantly reduced by transient expression of an Itk mutant lacking the kinase activity. The reduction paralleled a decrease in tyrosine phosphorylation of endogenous wild-type Itk. Stimulation of CD2 or TCR/CD3 induced activation of the nuclear factor of activated T cells (NFAT), the binding site of which is included in the IL-2 gene promoter. The activation of NFAT was also impaired by expression of the Itk mutant. These results demonstrate that Itk plays a role in IL-2 production, indicating a critical involvement of Itk in the initial stage of T cell activation by mediating signals from the TCR/CD3 complex, CD2, and CD28.

CD2 Antigens↗
PubMed1996

Zeta chain and CD28 are poorly expressed on T lymphocytes from chronic lymphocytic leukemia.

We have analyzed the expression of the zeta chain of the T cell receptor/CD3 complex and the co-stimulatory molecule CD28 by dual colour immunofluorescence on T lymphocytes from patients with B cell chronic lymphocytic leukemia (CLL). Zeta chain was significantly reduced on CD3-positive lymphocytes from 33 patients compared with normal controls (P<0.0001). The values were lower in stages B and C than in stage A. In five patients tested in partial remission the values were normal. CD28, investigated in CD3, CD4 and CD8 positive T cells from 18 CLL patients appeared to be reduced in the three subsets but more marked in CD8-positive lymphocytes. The loss of zeta chain and CD28 in a proportion of circulating T lymphocytes from CLL may underlie some of the known functional abnormalities of these cells and the immunodeficiency associated with the disease.

CD28 Antigens↗
PubMed1983

Biosynthesis and molecular nature of the T3 antigen of human T lymphocytes.

Immunoprecipitates of the T3 antigen prepared from HPB-ALL cells by using the monoclonal antibody UCH-T1 were analysed by SDS-polyacrylamide gel electrophoresis. Cells which had been biosynthetically labelled for up to 4 h gave a major polypeptide of mol. wt. 19 000 plus two weaker, more diffuse bands of mol. wts. 21 000 and 23 000, whereas surface labelled cells gave a prominent band of mol. wt. 19 000, a major band of 21 000 and a weaker diffuse band of approximately 26 000. As judged from their sensitivity to proteinase-K digestion, all the above polypeptides possess a transmembrane orientation. Digestion with endoglycosidases H and F (endo-H and endo-F), and tunicamycin treatment indicate that all the polypeptides, except that of 19 000 mol. wt. are N-glycosylated. The 21 000 and 23 000 mol. wt. chains possess both immature and mature oligosaccharide units, whereas the 26 000 mol. wt. band apparently has mature units only. Pulse chase experiments combined with digestion by endo-F and endo-H suggest that the N-glycosylated polypeptides are derived from two polypeptides of mol. wts. 14 000 and 16 000. It is concluded that the T3 antigen is derived from three different non-glycosylated polypeptides two of which are subsequently N-glycosylated to give the 21 000, 23 000 and 26 000 forms. The cell surface T3 antigen most probably comprises at least two distinct, non-covalently associated polypeptides, but the number and types of polypeptides giving rise to the whole molecule and whether different complexes exist is at present unclear.

Antibodies, Monoclonal↗
PubMed2003

Fugu rubripes possesses genes for the entire set of the ITAM-bearing transmembrane signal subunits.

The transmembrane signaling subunits (TSSs) bearing the immunoreceptor tyrosine-based activation motif (ITAM) play a crucial role in triggering the effector functions of mammalian leukocytes. The involvement in key immune reactions and obvious extension through duplication events make TSSs valuable markers of the evolution of the immune system. We surveyed the genomic sequences of the teleostean fish Fugu rubripes for the presence of genes encoding these accessory molecules. Automatic gene prediction was not efficient because of the poor ability of the programs used to recognize the short exons encoding the intracellular regions of TSSs. However, the unique compactness of the Fugu genome and the conservation of the exon/intron arrangements of the TSS genes facilitated their recognition by visual inspection of the candidate genomic sequences. Evidence for the presence of the CD3epsilon, CD3gamma/delta, CD79a, CD79b, TCRzeta, FcRgamma, DAP12 and DAP10 genes in the Fugu genome was obtained. Furthermore, conserved synteny for the short regions including the TSS genes was revealed by comparison of the Fugu and human genomes. The data demonstrate that the set of TSSs arose before the teleost-tetrapod split and provide a starting point for experimental investigation of the molecular evolution of the leukocyte-activating receptor complexes from fish species to mammals.

Amino Acid Sequence↗
PubMed1992

Phospholipase C-gamma 1 association with CD3 structure in T cells.

Recently, we and others have reported tyrosine phosphorylation of phospholipase C-gamma 1 (PLC gamma 1) enzyme after CD3 activation of T cells, and have proposed that PLC gamma 1 mediates signal transduction through the T cell receptor (TCR/CD3). Here, using immunoblotting and immune complex PLC assays, we show that CD3 stimulation of Jurkat cells induces the association of PLC gamma 1 enzyme with CD3 complex. PLC activity is also found to co-precipitate with the CD3 zeta chain from activated cells. In addition, in vitro PLC assays show that CD3 activation leads to about 10-fold stimulation of PLC gamma 1 activity. These results, along with the observation that Jurkat cells preferentially express PLC gamma 1, indicate that PLC gamma 1 participates in CD3 signaling.

Antigens, Differentiation, T-Lymphocyte↗
PubMed2026

Functional and Proteomic Profiles of CD3(+) Plasma-Derived Small Extracellular Vesicles Differentiate Cancer Patients From Healthy Donors.

Small extracellular vesicles (sEV) released by T cells play a key role in immune regulation. Immune capture with anti-CD3 antibodies was used to isolate and study T cell-derived CD3(+)sEV from the plasma of patients with melanoma (MPs) or healthy donors (HDs). Functional responses induced in recipient target cells by CD3(+)sEV of MPs differed from responses induced by CD3(+)sEV of HDs. Approximating functions mediated by melanoma cell-derived sEV (MTEX), CD3(+)sEV of MPs reduced metabolic activity and proliferation of T cells while promoting activity in Mel526 cell targets. Proteomics profiling confirmed functional differences between CD3(+)sEV of MPs and HDs. Of 294 sEV-specific proteins identified in CD3(+)sEV, 226 were detected in the parent T cell proteome, confirming that the CD3(+)sEV proteome mimics that of the parent T lymphocytes. Among them were 66 differentially expressed proteins (DEPs) that differentiated vesicles from MPs and HDs. These DEPs were associated with processes linked to cancer-related functions. DEPs upregulated in CD3(+)sEV of MPs were associated with RHO-GTPase, cytokine, and MAPK signaling pathways. Thus, T cells of MPs were reprogrammed by MTEX to produce CD3(+)sEV that functionally resembled MTEX, partly recapitulated features of the tumor proteome, and differed from CD3(+)sEV of HDs. In cancer, the TEX-rewired T cells produce CD3(+)sEV that potentially could serve as a liquid biopsy of patients' T cells.

Humans↗
PubMed1997

Specific activation of resting T cells against CA19-9+ tumor cells by an anti-CD3/CA19-9 bispecific antibody in combination with a costimulatory anti-CD28 antibody.

Specific activation of resting lymphocytes for tumor targeting can be achieved by bispecific monoclonal antibodies (bi-mAb) with specificity for tumor antigens and T-cell-activating antigens, respectively, in combination with a costimulatory anti-CD28 antibody. We describe the generation and function of a bi-mAb with specificity for CD3 and for the tumor antigen CA19-9. The bi-mAb OKT3/NSI19-9 was generated by somatic fusion of two hybridoma lines secreting antibodies against CA19-9 and CD3, respectively. A hybrid/hybridoma was established, and its bi-mAb was characterized. In combination with a costimulatory anti-CD28 mAb resting peripheral lymphocytes could be activated specifically with T-cell proliferation and secretion of high amounts of interferon-gamma. On specific T-cell activation, bi-mAb OKT3/NSI19-9 could also redirect the cytotoxic effects of these T cells toward CA19-9+ tumor cells in vitro. Our results indicate that specific activation of resting T cells with bi-mAb OKT3/NSI19-9 in combination with an anti-CD28 mAb can activate resting T cells specifically and leads to antigen-dependent bi-mAb-mediated cytotoxicity against CA19-9+ target cells. This approach may offer new perspectives for the specific immunotherapy of CA19-9+ tumors.

Antibodies, Bispecific↗
PubMed1999

A humanized anti-CD3 antibody, HuM291, with low mitogenic activity, mediates complete and reversible T-cell depletion in chimpanzees.

BACKGROUND: An anti-CD3 antibody that reduces cytokine release syndrome (CRS) while maintaining immunosuppression would be a major advance in the treatment of acute allograft rejection. A humanized (Hu) anti-CD3 IgG2 Ab, HuM291 gamma2 M3 (HuM291; Protein Design Labs, Inc., Mountain View, CA), was engineered with mutations in the upper CH2 region of the Fc domain. The mutations were intended to reduce affinity for Fcgamma receptors, thought to be relevant to CRS. METHODS: In vitro studies using chimpanzee peripheral blood mononuclear cells (PBMCs) were conducted to characterize HuM291 and to establish an animal model. A multidose study was conducted in chimpanzees to evaluate the safety, pharmacokinetics, immunomodulatory activity, and immunogenicity of HuM291, when administered at doses ranging from 0.1 to 10 mg. RESULTS: HuM291 bound to and effectively downmodulated CD3 from chimpanzee PBMCs and stimulated substantially less cytokine secretion and proliferation of chimpanzee PBMCs compared with OKT3 (Orthoclone OKT3; Ortho Pharmaceutical Corp., Raritan, NJ). Multiple doses of HuM291 (0.1, 1.0, or 10 mg/dose) were not associated with adverse events, signs of toxicity, or CRS, despite cytokine release. HuM291 exhibited a long elimination t1/2 (81.5 hr) and, after three 10-mg doses, sustained serum concentrations > 1000 ng/ml were maintained for 1 week. Multiple 10-mg doses induced complete depletion of circulating CD2+CD3+ T cells for up to 10 days after the last dose; T cells recovered by Day 28. Anti-HuM291 Abs were observed in only 4 of 12 animals and were transient in 2 of those animals. CONCLUSIONS: In vitro, HuM291 is substantially less mitogenic than OKT3. In chimpanzees, HuM291 effectively depleted peripheral T cells without eliciting clinical signs of CRS, and recovered T cells were functionally normal.

Animals↗
PubMed1992

Interaction of CD4:lck with the T cell receptor/CD3 complex induces early signaling events in the absence of CD45 tyrosine phosphatase.

Antibody-mediated ligation of the CD3/T cell antigen receptor (TcR) activates phospholipase C (PLC) via a tyrosine kinase signaling pathway that requires expression of the transmembrane tyrosine phosphatase CD45. In normal T cells, CD3-mediated PLC activation is significantly augmented by co-ligation of CD3 with the CD4 co-receptor; however, unlike CD3-associated tyrosine kinases, antibody-induced activation of the CD4-associated tyrosine kinase p56lck does not require CD45 expression. To explore the role of CD45 in the CD3 and CD4 activation pathways further, we examined the effect of CD3/CD4 cross-linking on tyrosine phosphorylation and activation of phospholipase C in CD45- mutant cells of the T cell leukemia line HPB.ALL. In accord with previous observations, anti-CD3 stimulation of the CD45-deficient cells failed to activate tyrosine kinases, or PLC as measured by mobilization of intracellular calcium. However, we show here that ligation of CD3 with CD4 leads to tyrosine phosphorylation of PLC gamma 1 and elevation in the intracellular free Ca2+ concentration in CD45- cells that is in excess of that seen in CD45+ cells. Since CD4 stimulation alone did not activate PLC, a component of the CD3 signaling pathway must be independent of CD45. Anti-CD4-induced tyrosine phosphorylation and activation of CD4-associated lck was also enhanced in CD45- cells, suggesting that increased lck activation compensates for the defect in CD3/TcR signaling, such that interaction of the CD3 signaling pathway with the CD4-associated pathway activates PLC even in the absence of CD45. The data demonstrate that the requirement for CD45 in coupling CD3/TcR to the PI-PLC activation cascade is not absolute, but rather substantiates a role for CD45 in modifying molecular interactions that control T cell activation.

Antigens, CD↗
PubMed1997

Differential T cell receptor-mediated signaling in naive and memory CD4 T cells.

Naive and memory CD4 T cells differ in cell surface phenotype, function, activation requirements, and modes of regulation. To investigate the molecular bases for the dichotomies between naive and memory CD4 T cells and to understand how the T cell receptor (TCR) directs diverse functional outcomes, we investigated proximal signaling events triggered through the TCR/CD3 complex in naive and memory CD4 T cell subsets isolated on the basis of CD45 isoform expression. Naive CD4 T cells signal through TCR/CD3 similar to unseparated CD4 T cells, producing multiple tyrosine-phosphorylated protein species overall and phosphorylating the T cell-specific ZAP-70 tyrosine kinase which is recruited to the CD3zeta subunit of the TCR. Memory CD4 T cells, however, exhibit a unique pattern of signaling through TCR/CD3. Following stimulation through TCR/CD3, memory CD4 T cells produce fewer species of tyrosine-phosphorylated substrates and fail to phosphorylate ZAP-70, yet unphosphorylated ZAP-70 can associate with the TCR/CD3 complex. Moreover, a 26/28-kDa phosphorylated doublet is associated with CD3zeta in resting and activated memory but not in naive CD4 T cells. Despite these differences in the phosphorylation of ZAP-70 and CD3-associated proteins, the ZAP-70-related kinase, p72syk, exhibits similar phosphorylation in naive and memory T cell subsets, suggesting that this kinase could function in place of ZAP-70 in memory CD4 T cells. These results indicate that proximal signals are differentially coupled to the TCR in naive versus memory CD4 T cells, potentially leading to distinct downstream signaling events and ultimately to the diverse functions elicited by these two CD4 T cell subsets.

Amino Acid Sequence↗