The effects of in vivo hydrocortisone on lymphocyte-mediated cytotoxicity

To examine the effects of in vivo hydrocortisone sodium succinate (HC) on natural killer (NK) cell and antibody-dependent cellular cytotoxicity (ADCC), 11 normal adults received a single intravenous bolus of 400 mg hydrocortisone. Lymphocytes were tested for NK activity and ADCC using 51chromium (51Cr)-release and single cell cytotoxicity assays against Molt-4 and sensitized RL O leads to target cells, respectively. Four hours after injection, both NK and ADCC activity were transiently increased in the 51Cr-release system (P less than 0.05). At 4 hours, there was a twofold increase in the relative frequency of potentially cytotoxic target binding cells (P less than 0.001) but the absolute number of these cells did not change (P less than 0.1). However, the percentage lysis of bound targets at 4 hours was not altered (P greater than 0.1). These data suggest that: 1) lymphocytes participating in NK and ADCC reactions are refractory to the kinetic and functional effects of HC; 2) the increased lytic activity observed at 4 hours is due to a selective depletion of noncytotoxic cells from the circulation; and 3) NK and ADCC activity did not differ in their responses to HC.