Suppression of phagocytosis and XXXX by cell wall components of @entity794 .

@entity1 @entity6722 @entity794 @entity11845
The ability of @entity794 to resist phagocytosis by polymorphonuclear leukocytes (PMN) is thought to be an important virulence factor for this microorganism. We have studied the effect of 3 major cell wall components of @entity794 , peptidoglycan, protein A, and @entity11845 , on PMN function. Phagocytosis and @entity6722 were both inhibited by prior incubation of PMN with peptidoglycan. This effect was dose- and time-related; incubation with as little as 2.5 micrograms/ml for 30 min produced a discernible suppressive effect. Suppression of PMN function was independent of the presence of human serum but was abolished by rabbit antiserum to peptidoglycan. Addition of peptidoglycan to PMN stimulated a prolonged chemiluminescence response that was greater when the peptidoglycan was first incubated in normal serum, perhaps reflection opsonization of this particulate material. Although protein A also suppressed phagocytic and chemotactic capabilities of PMN, this effect was observed only in the presence of serum and was eliminated by absorbing Ig. Centrifugation of the serum + protein A mixture showed that the suppressive effect was contained in the precipitated sediment. Complexes of Ig alone were not suppressive. @entity11845 in concentrations less than or equal to 100 micrograms/ml had no adverse effect on PMN function. These studies describe ways in which peptidoglycan and protein A may interfere with phagocytosis and @entity6722 of @entity1 PMN, thus giving evidence for the role of these cell wall components as virulence factors.
