Comparison of roles of serine esterase in chicken and human natural cytotoxicity.

The requirements for serine esterase activity in the spontaneous cell-mediated cytotoxicity of human lymphocytes and chicken granulocytes have been compared. The lysis of K-562 target cells and of LSCC-H32 chicken target cells was prevented by the serine esterase inhibitor TPCK. ATEE, the substrate of chymotrypsin, impaired both cytotoxic reactions, but to a lesser degree the cytotoxicity of chicken granulocytes. TPCK inhibited the "trigger" mechanism in an early calcium-dependent step and later calcium-independent events in both systems. However, calcium-independent lysis was depressed by serine esterase inhibitor only in the avian cytotoxicity. These findings suggest that avian target cell cytolysis consists of similar sequential phases to those already demonstrated in the human NK cell reaction, and serine esterase is required during several stages of cytotoxicity in the avian system.