The effects of neuraminidase on concanavalin a agglutination of erythrocytes: Evidence for adsorption of neuraminidase to erythrocyte membrane

Abstract

Neuraminidase‐treated human erythrocytes, but not untreated erythrocytes, were agglutinated by concanavalin A. The degree of concanavalin A agglutinability was not directly related to sialic acid removal by neuraminidase. While maximal sialic acid release was obtained with 5 units neuraminidase/2 × 10⁹ erythrocytes, maximal concanavalin A agglutination was only obtained after exposure to 20 units neuraminidase. Binding of ³H‐concanavalin A by erythrocytes was 10‐fold higher with rabbit compared to human red cells.Neuraminidase treatment of human erythrocytes caused a relative increase in ³H‐concanavalin binding, but the absolute amount was still 10‐fold less than that bound to rabbit erythrocytes. Specific adherence of neuraminidase to Con A‐Agarose could not be demonstrated. There was no evidence for contamination of the neuraminidase preparation with proteases using a sensitive assay. These studies suggest that neuraminidase adsorbs to erythrocyte membranes and leads to concanavalin A agglutination of human erythrocytes by a mechanism other than removal of sialic acid.