Antigenic activity of extracts of pneumococci

Abstract

Antigenic substances have recently been extracted in soluble form from many bacteria, and the work of Boivin & Mesrobeanu (1934), Raistrick & Topley (1934) and Topley et al. (1937) has shown that polysaccharides in combination with other non-protein substances extracted from certain Gram-negative bacilli stimulate an effective immunity in mice and specific antibody formation in rabbits. The antigenicity of similar extracts of pneumococci has not been so readily demonstrated. Berkefeld filtrates of pneumococci lysed by bile or by alternate freezing and thawing were found to be non-antigenic in rabbits (Avery & Morgan, 1925; Avery & Neill, 1925), although it was possible to immunize mice effectively with bacteria-free solutions obtained from cultures of pneumococci (Perlzweig & Steffen, 1923; Perlzweig & Keefer, 1925; Meyer, 1927). The essential antigen for the production of immunity in mice has been shown to be the type-specific polysaccharide which is effective only in small doses, usually between 0.01 and 0.00001 mg. (Schiemann & Caspar, 1927; Schiemann, 1929; Enders, 1930; Wadsworth & Brown, 1931; Avery & Goebel, 1933). The type-specific polysaccharide has, however, been found to be without antigenic activity in rabbits (Avery & Goebel, 1933; Downie, 1937).