Studies of Phagocytosis of Group a Streptococci by Polymorphonuclear Leucocytes in Vitro

Abstract

When Group A streptococci are mixed with human blood under appropriate conditions in vitro, the bacteria are rapidly engulfed and killed by leucocytes. Among the conditions (1) required for this reaction are: (a) sufficiently large numbers of leucocytes, (b) complement and perhaps other serum or plasma factors, (c) an efficient mixing system to ensure adequate opportunity for contact between the white cells and streptococci, and (d) type-specific antibody, which is necessary for phagocytosis only in the case of streptococcal strains containing M protein.Efforts to develop an opsonophagocytic test for Group A streptococci, employing rabbit or mouse blood, have been "unsuccessful. The lack of bactericidal action in blood of these animals has been attributed by some to failure of the leucocytes to kill engulfed microorganisms (2, 3), while others have implicated deficiencies in plasma factors and inadequate phagocytosis (1, 4). Furthermore, recent studies have demonstrated that the differences between rabbit and human blood are not entirely consistent in this regard; blood from certain apparently healthy human beings is not satisfactory for use in the bactericidal test on streptococci, while on rare occasions a rabbit is found whose blood serves quite well for this purpose (5).This communication presents studies on interactions between polymorphonuclear leucocytes and Group A streptococci in vitro. The results indicate that under certain conditions an anti-phagocytic effect is exerted by the streptococcal hyaluronic acid capsule as well as by M protein. All human plasma or serum specimens thus far studied contain a factor, apparently neither enzyme nor antibody in nature, which counteracts the phagocytosis-resisting action of the capsule. In contrast, rabbit serum appears to be devoid of this factor. MethodsPeritoneal exudates were collected from adult New Zealand Red rabbits by a technique previously described (6), with slight modifications. The essential features of this procedure were as follows. Three hundred ml. of sterile isotonic saline containing 1 rag. per ml. glycogen *

The Relationship Between Group a and Group C Meningococcal Polysaccharides and Serum Opsonins in Man

“…Results after absorption of these sera with log-phase bacteria and meningococcal polysaccharides suggest that these polysaccharides are the major antiphagocytic determinants for groups A and C meningococci. Minor determinants should also be kept in mind since such factors have been described for other bacteria-phagocyte interactions (17,18).…”

The Role of Complement in Immune Phagocytosis of Group A Streptococci by Mouse Peritoneal Phagocytic Cells

“…It has been shown that efficient phagocytosis of virulent, encapsulated group A streptococci by human blood requires, in addition to homologous type-specific anti-M antibody, a thermo-labile factor which has been termed "streptococcal co -opsonin" [26]. This factor appears to be independent of complement and to be directed against the hyaluronate capsule of the streptococcus [10]. However, a few questions still remain whether the coopsonin is required for efficient phagocytosis of only encapsulated streptococcal strains [26].…”

The Virulence of Biochemical Variants of Streptococcus pyogenes

“…1959;Hirsch & Church, 1960). The variants both formed mucoid colonies; both produced well defined but not outstandingly large capsules in 2.5 hr broth cultures.…”