Effects of lectins on the hemolysis of rabbit erythrocytes by straphylococcal alpha toxin

Abstract

When concanavalin A (1 microgram/ml) or wheat germ agglutinin (2 microgram/ml) was preincubated with a suspension of 2% rabbit erythrocytes for 5 min at 20 C, the binding [125I]-labeled staphylococcal alpha toxin to these erythrocytes was greatly inhibited and the hemolytic action of alpha toxin was decreased. The inhibitory effect of concanavalin A on hemolysis by alpha toxin was completely reversed in the presence of 0.1 M alpha-methyl-D-glucoside or alpha-methyl-D-mannoside. Phytohemagglutinin-P from Phaseolus vulgaris and soybean agglutinin inhibited hemolysis by the toxin at concentrations exceeding 20 microgram/ml. The effect of concanavalin A on alpha-toxin hemolysis was studied further to ascertain the nature of the inhibition. Double reciprocal plots were made of hemolysis against alpha toxin concentrations, and the data suggested that inhibition of the initial rate of the hemolysis by concanavalin A is competitive in nature. This was probably due to an interaction with the alpha toxin binding sites on the cell membrane surface.