CHEMICAL STUDIES ON BACTERIAL AGGLUTINATION : VII. A QUANTITATIVE STUDY OF THE TYPE SPECIFIC AND GROUP SPECIFIC ANTIBODIES IN ANTIMENINGOCOCCAL SERA OF VARIOUS SPECIES AND THEIR RELATION TO MOUSE PROTECTION.

1. The quantitative method for the estimation of agglutinins has been applied to antimeningococcal horse, rabbit, and chicken sera and to the sera of humans convalescing from meningococcus meningitis. The type-specific and group-specific agglutinin N can be measured, using homologous and heterologous suspensions of meningococci. 2. Type I horse, rabbit, and chicken antimeningococcal sera contain considerable amounts of antibody which cannot be removed either by Type II meningococcus suspension or by preparations of the Type I specific polysaccharide. This residual type-specific antibody has marked potency in protecting mice against subsequent infection with meningococci. 3. Most human convalescent sera contain group-specific antibody. Small amounts of protective antibody and of antipolysaccharide are also formed. 4. Type I antisera absorbed with Type I polysaccharide and with Type II meningococci could be used as a guide in the purification of this new antigen.