Effect of histamine-receptor blocking on human spontaneous lymphocyte-mediated cytotoxicity

The effect of H1- and h2-receptor-blocking agents on spontaneous lymphocyte-mediated cytotoxicity (SLMC) was studied. The H1-receptor blocker clemastinum and the H2-receptor blocker cimetidine inhibited the spontaneous cytotoxic activity of normal human peripheral blood lymphocytes on K-562 target cells dose-dependently. The inhibition cannot be explained either by a direct toxic effect on natural killer (NK) cells or by blocking of Fc receptors. The possible involvement of histamine receptor-bearing lymphocytes in human SLMC is suggested.