Streptococcus mutans to Phagocytosis by Human

To clarify the role of cell surface components of Streptococcus mutans in resistance to phagocytosis by human polymorphonuclear leukocytes (PMNs), several isogenic mutants of S. mutans defective in cell surface com-ponents were studied with a luminol-enhanced chemiluminescence (CL) assay, a killing assay, and a trans-mission electron microscope. The CL responses of human PMNs to mutant Xc11 defective in a major cell surface antigen, PAc, and mutant Xc16 defective in two surface glucosyltransferases (GTF-I and GTF-SI) were the same as the response to the wild-type strain, Xc. In contrast, mutant Xc24R, which was defective in serotype c-specific polysaccharide, induced a markedly higher CL response than the other strains. The killing assay showed that human PMNs killed more Xc24R than the parent strain and the other mutants. The transmissio