Some Factors affecting the Cytotoxic Immune Reaction of Rat Mast Cells

Abstract

EARLIER investigations have shown that incubation of isolated rat peritoneal mast cells with purified anti-rat IgG-globulin and fresh serum in vitro results in a cytotoxic immune reaction¹. Data demonstrating that this process is inhibited by various agents, especially by alkyl phosphates and synthetic chymotrypsin substrates, indicate that the activation of a chymotrypsin-like esterase is of some importance for the reaction². The enzyme, which is contained in the heat labile serum portion, shows many striking similarities to an enzyme of the complement complex (C′₁-esterase), and was therefore thought to be identical with it³. Further experiments, however, revealed that neither a euglobulin preparation with high C′₁-esterase activity nor purified human (C′_1a-esterase, irrespective of whether or not antibody is also present, produces detectable morphological or pharmacological changes in isolated rat mast cells (ref. 3 and Lepow, I. H., personal communication). The question thus arose as to what extent the immunological behaviour of mast cells would be influenced by pre-treatment with various enzymes. The data presented here provide some insight into the problem.