Both immature and mature T cells mobilize Ca2+ in response to antigen receptor crosslinking.
T cells develop from prothymocytes which express no detectable antigen receptors to immature thymocytes with few receptors, eventually becoming mature thymocytes and peripheral T cells with 20,000-40,000 receptors per cell. Recent studies suggest that immature thymocytes are immunologically unresponsive. We have suggested that an early step in signal transduction following engagement of the T cell receptor might differ in immature and mature T cells. Here we examine anti-receptor antibody mediated induction of calcium mobilization in immature and mature T cells. Results indicate that antigen receptors on both immature and mature receptor-positive T cells transduce signals via calcium mobilization. Significant differences were observed, however, between these populations in the magnitude of influx of extracellular Ca2+ following binding of antireceptor antibody. Specifically immature cells show a much reduced Ca2+ influx response compared to mature cells which could result from a low Ca2+ channel frequency in the plasma membranes of immature T cells, or from less efficient activation of existing channels.
D000818:Animals; D000906:Antibodies; D000936:Antigen-Antibody Complex; D002118:Calcium / Q000378:metabolism*; D005434:Flow Cytometry; D007700:Kinetics; D008213:Lymphocyte Activation; D051379:Mice; D008809:Mice, Inbred C3H; D011948:Receptors, Antigen, T-Cell / Q000502:physiology*; D013601:T-Lymphocytes / Q000166:cytology / Q000276:immunology* / Q000378:metabolism; D013950:Thymus Gland / Q000276:immunology
D000906:Antibodies; D000936:Antigen-Antibody Complex; D011948:Receptors, Antigen, T-Cell; D002118:Calcium