The effects of protease inhibitors on lymphocyte transformation.

Abstract

This work presents an investigation of the effects of various protease inhibitors but mainly soybean trypsin inhibitor (SBI) on transformation of human and mouse lymphocytes induced by a variety of agents. SBI was found to inhibit transformation of human lymphocytes induced by mitogens (leucoagglutinin, concanavalin A, NaIO4, phytohemagglutinin, pokeweed mitogen) or in the mixed lymphocyte reaction. Other protein protease inhibitors which were effective were lima bean trypsin inhibitor (LBI) and ovomucoid (OM). Synthetic protease inhibitors which were effective were N-tosyl-L-Lysine-chloromethyl-ketone (TLCK), tosyl-phenylalanyl-chloromethyl ketone (TPCK), N-tosyl-L-argine methyl ester (TAME), phenyl-methylsulfonylfluoride (PMSF) and epsilon-aminocaproic acid (EACA). Exposure of the cultures to the inhibitors did not affect the viability of the cells. SBI covalently cross-linked to sepharose beads also inhibited the MLR and mitogen stimulation. Kinetic studies, done with human and mouse cells, showed that the inhibitor acted early after the addition of the mitogen or the mixing of the allogenic cells in the MLR. The effect of the plasma and of other cell types present in the cultures on the degree of inhibition was also investigated. The data shown support the hypothesis that protease action at a cell surface is an essential early event common to all types of lymphocyte transformation.