The binding of Pneumococcal lipoteichoic acid to human erythrocytes

Previous studies have evaluated the binding characteristics of lipoteichoic acids (LTA) composed of polyglycerol phosphate to mammalian cell membranes. This present study was performed to evaluate the binding characteristics of Pneumococcal LTA, a polyribitol phosphate containing LTA, to human erythrocytes. Binding was found to be specific, reversible, and dependent on temperature and time. Maximum binding was achieved within 2 h at 37 degrees C. Scatchard plot analysis of the binding revealed a biphasic plot which suggests two receptor sites with different affinities. Competitive inhibition studies with LTA composed of polyglycerol phosphate and isolated from Streptococcus pyogenes and Lactobacillus fermentum revealed significant inhibition of Pneumococcal LTA-binding to the erythrocyte membrane by these heterologous LTAs. These results demonstrate that Pneumococcal LTA binds specifically to human erythrocytes and that the receptor site is similar for other structurally different LTAs.