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Limited specific T-cell mediated cytolysis in the absence of extracellular Ca2+
Mouse lymphocytes sensitized either in vitro or in vivo with allogeneic cells were analysed for their cytolytic activity incomplete or Ca2+-deprived medium. The deprived medium was obtained by adding EGTA in excess of the molar Ca2+ concentration but not exceeding that of Ca2+ plus Mg2+. The cytolysis in complete medium was between five and thirty-fold greater in terms of lytic units, than that in Ca2+-deprived medium. This applied equally for effectors sensitized in vivo or in vitro although the overall lytic capacity of the former was greater. The cytolysis in Ca2+-deprived medium was judged to be Mg2+ dependent, as little or no cytolysis was seen if EDTA was added to cultures in a molar concentration exceeding that of Ca2+ plus Mg2+. Direct comparison of cytolysis in complete and deprived medium showed no difference between effectors in the two situations with respect to (a) adherence to nylon wool; (b) sensitivity to lysis by anti-Thy-1.2 antiserum and complement; (c) specificity of lysis; (d) rate of cytolysis with time when effector cell numbers were adjusted to give equal levels of cytolysis at any one time; and (e) shape and angle of the slope of 51Cr release against log increase in effector cell numbers where target cell numbers were constant.
Mouse lymphocytes sensitized either in vitro or in vivo with allogeneic cells were analysed for their cytolytic activity incomplete or Ca2+-deprived medium. The deprived medium was obtained by adding EGTA in excess of the molar Ca2+ concentration but not exceeding that of Ca2+ plus Mg2+. The cytolysis in complete medium was between five and thirty-fold greater in terms of lytic units, than that in Ca2+-deprived medium. This applied equally for effectors sensitized in vivo or in vitro although the overall lytic capacity of the former was greater. The cytolysis in Ca2+-deprived medium was judged to be Mg2+ dependent, as little or no cytolysis was seen if EDTA was added to cultures in a molar concentration exceeding that of Ca2+ plus Mg2+. Direct comparison of cytolysis in complete and deprived medium showed no difference between effectors in the two situations with respect to (a) adherence to nylon wool; (b) sensitivity to lysis by anti-Thy-1.2 antiserum and complement; (c) specificity of lysis; (d) rate of cytolysis with time when effector cell numbers were adjusted to give equal levels of cytolysis at any one time; and (e) shape and angle of the slope of 51Cr release against log increase in effector cell numbers where target cell numbers were constant.