[Interaction of group A streptococci with a culture of HEp-2 cells].

An initial stage of the interaction of the virulent (matt) and avirulent (glossy) strains of group A streptococcus with the human epithelial tissue (Hep-2) was studied. M+ and M- variants of three strains of group A streptococcus belonging to serological types 2 and 4 possessed different biological activity against the Hep-2 epithelial cells in the monolayer. M+-variant actively affected the great majority of the cells of the monolayer, multiplied of their surface and formed microcolonies. M--variant affected only an insignificant number of cells and failed to multiply on them. In difference from M+-streptococci, the activity of M+-variants is explained by their capacity to adhere to the surface of the animal cells irreversibly. This process started immediately and terminated by 1 1/2 hours of the microbial incubation in vitro with the Hep-2 monolayer. Trypsin treatment of M+-streptococci sharply diminished their capacity to adhesion, this apparently being the result of M-protein digestion. The data presented point to the important role played by M-protein in the phenomenon of the streptococci adhesion to the epithelial cells.