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 → target cells, respectively. Four hours after injection, both NK and ADCC activity were transiently increased in the ⁵¹Cr-release system (P < 0.05). At 4 hours, there was a twofold increase in the relative frequency of potentially cytotoxic target binding cells (P < 0.001) but the absolute number of these cells did not change (P < 0.1). However, the percentage lysis of bound targets at 4 hours was not altered (P > 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.