ANTIGENS OF TYPE II PNEUMOCOCCUS CELLS

Avery and Heidelberger and their associates (1-4) have presented convincing evidence that the virulent pneumococcus cell contains two different types of antigens: (1) a type-specific antigen (SP) which gives rise to a type-specific antibody; (2) a species-specific antigen (p)l which gives rise to a species-specific antibody. The typespecific antigenic complex is contained in the intact cell of strains possessing the soluble specific substance; immunization of a suitable animal with suspensions of pneumococcal cells invokes a type-specific antibody which reacts specifically with the soluble specific substance whether contained in solution (S-precipitation) or disposed on the periphery of the bacterial cell (agglutination); the same antibody is also apparently the one responsible for the passive protection of mice, at least against Type I I pneumococci (5). The species-specific antigen, in contrast to the type-specific one, gives rise to an antibody