A triggering structure recognized by G7 monoclonal antibody on porcine lymphocytes and granulocytes

Monoclonal antibody (mAb) G7 has been developed and appears to recognize a triggering structure on porcine natural killer (NK) cells and granulocytes. G7 mAb binds to approximately 13% of lymphocytes, 70% of monocytes, and >95% of granulocytes. G7 mAb does not react with B cells. G7 mAb immunoprecipitates a heterodispersed molecule of ~40 kDa. Functionally, whole but not F(ab′) 2 fragments of G7 mAb enhance NK killing of Fc receptor positive K562, U937, and MOLT-4 targets but not Fc receptor negative CEM, WEHI-164, or YAC-1 targets. Both whole and F(ab′) 2 fragments of G7 mAb inhibit lymphocyte-mediated antibody-dependent cellular cytotoxicity. Interestingly, G7 mAb induces dramatic levels of granulocyte killing against nucleated K562 targets. These results suggest that G7 mAb recognizes a trigger molecule involved in porcine cellular cytotoxicity.