Induction of porcine granulocyte-mediated tumor cytotoxicity by two distinct monoclonal antibodies against lytic trigger molecules (PNK-E/G7).
PNK-E and G7 mAb bind to distinct porcine granulocyte function-associated molecules and induce granulocyte-mediated cytotoxicity against tumor targets. PNK-E mAb binds to a 205-kDa molecule that reduces to a dispersed band of 50 kDa on SDS-PAGE analysis. Previous work demonstrates that G7 mAb immunoprecipitates a molecule that appears as a heterodispersed 40-kDa band under both reducing and nonreducing conditions on SDS-PAGE analysis. Whole but not F(ab')2 PNK-E and G7 mAb induce dose-dependent porcine granulocyte-mediated lysis of FcR+ but not FcR- targets, suggesting a redirected cytotoxicity mechanism of granulocyte-mediated killing. Fresh porcine granulocytes also mediate significant levels of antibody-dependent cellular cytotoxicity (ADCC) against nucleated (SB) target cells. Neither whole nor F(ab')2 PNK-E mAb affects granulocyte-mediated ADCC against SB target cells. However, both whole and F(ab')2 G7 mAb inhibit granulocyte-mediated ADCC against SB targets by approximately 50%. Bound F(ab')2 G7 mAb inhibits PNK-E mAb-induced granulocyte-mediated cytotoxicity against K562 targets, but bound F(ab')2 PNK-E mAb does not inhibit G7 mAb-induced granulocyte-mediated cytotoxicity, suggesting a physical association between the PNK-E and G7 molecules on the surface of porcine granulocytes. PNK-E and G7 hybridoma cells are readily lysed by granulocyte effectors, further supporting that the PNK-E and G7 molecules are cytolytic trigger molecules on granulocytes. These data demonstrate that PNK-E and G7 mAb bind to distinct granulocyte lytic trigger molecules and induce potent granulocyte-mediated cytotoxicity against nucleated tumor targets through a mechanism of redirected cytotoxicity.
Wierda
W G
WG
Department of Microbiology and Immunology, University of Health Sciences, Chicago Medical School, IL 60064.
Johnson
B D
BD
Dato
M E
ME
Kim
Y B
YB
D000818:Animals; D000911:Antibodies, Monoclonal; D000920:Antibody-Dependent Cell Cytotoxicity; D005260:Female; D006098:Granulocytes / Q000276:immunology*; D006801:Humans; D066298:In Vitro Techniques; D007694:Killer Cells, Natural / Q000276:immunology; D008297:Male; D011961:Receptors, Fc / Q000378:metabolism; D013552:Swine; D013556:Swine, Miniature / Q000276:immunology*; D014407:Tumor Cells, Cultured / Q000276:immunology
D000911:Antibodies, Monoclonal; D011961:Receptors, Fc