Role of extracellular calcium ions at early stages of human T-lymphocyte polyclonal activation in vitro.

In this work we comparatively analyzed interleukin-2 (IL-2) and interferon gamma production (IFN-gamma) and also CD69 and CD25 expression by activated T-cells depending on extracellular calcium concentration ([Ca2+]e), which was varied with EGTA. The expression of CD69 molecules on the surface of T-cells depended only on the presence of phorbol myristate acetate, occurred at [Ca2+]e higher than 0.2 mM, and did not require the presence of ionomycin. The increase in [Ca2+]e by itself cannot induce expression of CD25 and CD69 molecules by activated cells. The values of [Ca2+]e, at which maximal fractions of CD3+CD69+(IL-2)+, CD3+CD69+(IFN-gamma)+, and CD3+CD25+ activated T-cells were reached, never coincided with mean values of [Ca2+]e for healthy donors and were different from each other. So, there is different [Ca2+]e dependence for initial stages of activated T-cells differentiation. The relation between T-cells activation parameters and their differentiation is discussed.