Lymphocytes of mice sensitized by injection of homologous cells are capable of lysing, in tissue culture, cells of the same type used for sensitization. The serum of such animals also may contain cytotoxic humoral antibodies. The purpose of the present study was to ascertain if the cytolytic effect of the lymphocytes was due to their functional modification or to adsorbed humoral cytotoxic antibodies. The experiments were conducted to determine differences in the effects of ionizing radiation and hydrocortisone on the cytolytic effects of antiserum and lymphocytes from sensitized mice. The lytic effect of the sensitized lymphocytes was completely abolished by x-irradiation (15,000 r) whereas the cytolytic effect of antiserum was not demonstrably affected by the same level of irradiation. Furthermore, addition of hydrocortisone to homologous cytotoxic serum did not alter the lytic effect; previous experiments with hydrocortisone carried out under the same conditions had demonstrated a marked reduction in cytolysis mediated by sensitized homologous lymphoid cells. Since the cytolytic effect of sensitized lymphocytes was abolished by irradiation and was partially suppressed by hydrocortisone but the cytolytic effect of antiserum remained unchanged, it was concluded that lysis was related to functional modification of the lymphocytes and not to adsorbed cytotoxic antibodies.


This study was supported by the United States Public Health Service, grants CA-07191-02 and CA-03341-08.

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