The role of M protein in phagocytosis. I. Activity of some enzymes in phagocytic cells during infection with Streptococcus pyogenes in vivo.

The phagocytosis of two type 12 Streptococcus pyogenes strains differing in M protein presence was investigated in vivo. The rate of phagocytosis and the streptococcal viability in phagocytic cells and outside of them was studied simultanously with estimation of enzymatic activity in phagocytic cells. It was observed that M positive strain was phagocytized at lower rate and also exhibited longer viability. Decrease of lactic dehydrogenase and ATP-ase activity in phagocytes of rabbits infected with M+ strain was also detected. These results suggest that M protein disturbs phagocytosis by inhibiting their main metabolic pathway of glycolysis.