Comparison of signals delivered through CD3 and CD2 for T-cell activation: the role of calcium influx and interleukin 1H Wakasugi et al. Hum Immunol. 1988 Nov. Show AbstractIn the absence of monocytes, resting T lymphocytes extensively purified from human peripheral blood failed to proliferate when stimulated with a mixture of calcium ionophore, which elevates intracellular calcium levels, and TPA, which activated protein kinase C. A third signal, i.e., the triggering via CD3 or CD2 molecules, was necessary in order to observe proliferation. These highly purified T cells required the presence of monocytes in both CD3 and CD2 systems for their proliferation. Exogenous interleukin 1 clearly substituted for monocytes in CD2- but not in CD3- triggered T-cell proliferation. In contrast, the effect of CD2 and CD3 antibodies on Ca++ influx was apparently not dependent on the presence of monocytes. In the presence or absence of the monocytes, CD3, as well as certain combinations of CD2 monoclonal antibodies including the D66 monoclonal antibody, were able to increase the intracellular calcium concentration as measured by Quin 2 fluorescence. EGTA, a Ca++ chelator, completely inhibited CD2- and CD3- mediated T-cell proliferation, indicating that calcium uptake is necessary during the T-cell proliferation. The addition of TPA abrogated the inhibitory effect of EGTA and completely restored the response of the T cells stimulated by CD3, but not by CD2, monoclonal antibodies. In the CD2 pathway, EGTA-inhibited proliferation of T cells could be completely restored by addition of exogenous interleukin 2 as well as exogenous recombinant interleukin 1. Our results indicate that EGTA inhibits the production of interleukin 1 but has no direct effect on either interleukin 2 production or on Tac antigen expression. In this system, recombinant interleukin 1 alpha demonstrated a more potent ability for restoring the T-cell response than did recombinant interleukin 1 beta. These results suggest that interleukin 1 could act as a potent costimulatory factor in the non-antigen-specific T-cell activation. PubMed Disclaimer Similar articles
Cited byT lymphocyte anergy during acute infectious mononucleosis is restricted to the clonotypic receptor activation pathway. The ability of purified T cells to be activated by immobilized anti-CD3 and soluble anti-CD2 monoclonal antibodies (mAbs) was compared using cells from young and old donors. Purified T cells from elderly humans activated with immobilized anti-CD3 mAb incorporated less [3H]thymidine (58,780 vs 92,258 cpm; p < 0.02) into cellular DNA, and secreted less IL-2 into the culture supernatants than did T cells from young donors. In contrast, T cells activated with anti-CD2 mAbs displayed no age-related differences in proliferation or IL-2 production. Anti-CD2 stimulation resulted in equal IL-2 synthesis by cells from young and old donors that was comparable to the amount produced by cells from elderly donors stimulated with immobilized anti-CD3. Northern blot analysis of early cell cycle gene expression by anti-CD2 activated T cells demonstrated no age differences in the expression of p55 IL-2R or c-myc specific mRNA, although T cells from elderly individuals activated with immobilized anti-CD3 showed statistically significant decreases in both mRNAs. T cell receptor beta chain mRNA levels did not differ between cells from young or old donors after activation by either anti-CD3 or anti-CD2. The discordance in proliferative ability, IL-2 secretion, and specific mRNA expression between T cells from elderly donors activated through the CD3-TCR complex or by soluble anti-CD2 mAbs provides additional evidence for a multifactorial causation of age-related T cell proliferative defects, and may indicate that the difference in proliferative ability is, in part, attributable to responsiveness to secreted IL-2. PubMed Disclaimer Similar articles
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