title: Enhanced phagocytosis of group A streptococci M type 6 by oleic acid.
abstract: M protein, located on the surface fimbriae of group A streptococci, is antiphagocytic by unknown means. It is known that oleic acid kills group A streptococci and distorts the fimbriae. The effect of oleic acid on phagocytosis of group A streptococci was examined. Phagocytosis of a strain possessing M protein (M+) and its M- variant was assessed by uptake of radiolabeled bacteria and by chemiluminescence. The M- but not the M+ streptococci were well phagocytized and induced chemiluminescence. Oleic acid-killed and heat-killed streptococci (both M+ and M-) were readily phagocytized and induced sustained chemiluminescence. M+ streptococci killed by ultraviolet irradiation were inefficiently phagocytized and did not induce chemiluminescence. Oleic acid-killed M+ streptococci absorbed type-specific antibody. An extract of M protein reduced the bactericidal capacity of oleic acid. It is proposed that oleic acid may bind to and alter the M protein of group A streptococci and thereby enhance phagocytosis.
mesh_terms: D000042:Absorption; D000918:Antibody Specificity; D000942:Antigens, Bacterial; D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins / Q000494:pharmacology / Q000502:physiology*; D001770:Blood Bactericidal Activity; D002352:Carrier Proteins; D006358:Hot Temperature; D008163:Luminescent Measurements; D009829:Oleic Acids / Q000494:pharmacology*; D010587:Phagocytosis / Q000187:drug effects*; D013297:Streptococcus pyogenes / Q000187:drug effects* / Q000528:radiation effects / Q000648:ultrastructure; D014466:Ultraviolet Rays
chemical_list: D000942:Antigens, Bacterial; D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins; D002352:Carrier Proteins; D009829:Oleic Acids; C014689:streptococcal M protein