title: Micro complement fixation assay for type-specific group A streptococcal antibody.
abstract: A micro complement fixation assay was devised to measure the type-specificity of anti-M antibody. Unabsorbed sera were from rabbits hyperimmunized with heat-killed streptococci and from humans with naturally occurring antibody or immunized with purified M protein vaccines. These sera fixed complement only in the presence of homologous M proteins (serotypes 1, 3, 6, 12, and 14). The complement fixation reaction paralleled the results obtained with the Lancefield bactericidal (opsonic) assay and did not exhibit the cross-reactions frequently seen with type-specific anti-M sera assayed by passive hemagglutination. All serological activity of the antisera resided in the fraction corresponding to 7S globulin eluted from a Sephadex G-200 gel filtration column. Because of the close correlation between micro complement fixation and the bactericidal assay for type-specific antibody, it is proposed that the micro complement fixation procedure, as we have described it, merits further evaluation as a substitute for the bactericidal test of immunity to group A streptococcal infection.
mesh_terms: D000818:Animals; D000888:Antibodies, Anti-Idiotypic / Q000032:analysis; D000907:Antibodies, Bacterial / Q000032:analysis* / Q000302:isolation & purification; D000942:Antigens, Bacterial / Q000302:isolation & purification; D001426:Bacterial Proteins / Q000302:isolation & purification; D001428:Bacterial Vaccines; D003168:Complement Fixation Tests; D005069:Evaluation Studies as Topic; D006386:Hemagglutination Tests; D006801:Humans; D005779:Immunodiffusion; D007074:Immunoglobulin G / Q000032:analysis; D007075:Immunoglobulin M / Q000032:analysis; D007223:Infant; D011817:Rabbits / Q000276:immunology; D013056:Spectrophotometry, Ultraviolet; D013291:Streptococcus / Q000276:immunology*
chemical_list: D000888:Antibodies, Anti-Idiotypic; D000907:Antibodies, Bacterial; D000942:Antigens, Bacterial; D001426:Bacterial Proteins; D001428:Bacterial Vaccines; D007074:Immunoglobulin G; D007075:Immunoglobulin M