S pneumoniae activates Lu/BCAM through desialylation of the erythrocyte membrane. (A) Effect of S pneumoniae, S aureus, and purified neuraminidase from V cholerae on α2,3-linked sialic acid content of erythrocytes using M amurensis lectin and flow cytometry (n = 3-6). (B) Effect of erythrocyte incubation with S pneumoniae, S aureus, and purified neuraminidase from V cholerae on Lu/BCAM-mediated erythrocyte adhesion frequency to laminin-α5 (n = 5-7). *P < .05; **P < .01; ***P < .001. ns, not significant.