The mechanisms involved in the production of red cell panagglutinability by streptococcal cultures.

An agent capable of modifying red cells antigenically so that these become agglutinable by immune serum prepared against influenza virus treated cells has been identified in cultures of pneumococci and of many strains of streptococci, particularly streptococci of viridans type. This agent is believed to be the receptor-destroying enzyme. A total of four heat-stable red cell sensitizing antigens, probably polysaccharide in nature, have also been detected in streptococcal cultures. Antibodies to all four antigens are present in normal human sera. The presence of one of these antigens has been found to be almost completely negatively correlated with that of the cell-modifying (or receptor-destroying) enzyme. This antigen has been identified in most Lancefield Group streptococci, in some viridans streptococci, and in all strains of and examined, but appears to be absent from pneumococci. The other three antigens appear to be typical of the viridans streptococci and permit a serological subdivision of this group.