Abstract
Three cell surface antigens, protein, lipopolysaccharide, and polysaccharide, were purified from group B and group C strains of Neisseria meningitidis representing a variety of serotypes. Chemical analysis indicated that cross-contamination was on the order of 1%. Sensitization of sheep erythrocytes with these antigens resulted in highly specific passive hemagglutination assays for the three kinds of antigens. Paired human sera from several groups of individuals were tested by hemagglutination for antibody against each of the antigens. Patients with group B or C systemic meningococcal disease showed increases in antibody titer against all three kinds of antigens, but the antibody response to B polysaccharide was low compared with the response to C polysaccharide. Nasopharyngeal carriers of group B meningococci showed significant increases in titer only against the protein antigens, and noncarriers who received a C-polysaccharide vaccine had a specific response to the C polysaccharide. A given protein or lipopolysaccharide antigen reacted on the average equally well with either group B or C convalescent sera. These results suggest that all three antigens may play a role in the broad human immunity following natural infection.