TUMOR-CELL LYSIS MEDIATED BY IGG OR F(AB1)2 ANTIBODY FRAGMENTS AND COMPLEMENT

Abstract

Purified anti-P815 IgG or F(ab1)2 from rabbits or sheep were measured for lytic capacity on 51Cr-labelled murine P815 tumour cells with complement from either rabbits, sheep, rats or guinea-pigs. Rabbit IgG caused lysis with all complement sources but sheep IgG was lytic only with rabbit and sheep complements. Rabbit F(ab1)2 fragments caused target cell lysis with rabbit and sheep complements but not with rat or guinea-pig; sheep (F(ab1)2 was lytic only with rabbit complement. Using EGTA to remove Ca2+ from the assay system sheep and rabbit complements were variably activated via either the classical or alternate pathways, but rat and guinea-pig complements were activated only via the classi..