K cell mediated haemolysis: influence of large numbers of unsensitized cells on the antibody-dependent lysis of anti-D-sensitized erythrocytes by human lymphocytes.

The inhibition of K cell mediated haemolysis of anti-D-sensitized human red blood cells by unsensitized erythrocytes has been demonstrated. Inhibition of lysis was non-competitive in nature and influenced by the size and number of unsensitized cells. However, even in the presence of high inhibitor: target cell ratios (50:1) haemolysis, although reduced, was still effected suggesting that K cells are highly motile and capable of recognizing and destroying minority populations of antibody-sensitized erythrocytes. These data are compatible with a role for cytotoxic lymphocytes in the intravascular lysis of autoantibody or alloantibody-sensitized red cells.