A polysaccharide-protein complex from Haemophilus influenzae type b. II. Human antibodies to its somatic components.

A polysaccharide-protein complex prepared from Haemophilus influenzae type b strain Eagan was used as test antigen in an enzyme-linked immunosorbent assay for human serum antibodies. With washing buffer that did not contain detergent, the assay detected antibody to lipopolysaccharide (LPS) and to non-LPS somatic antigens as well as to polyribosylribitolphosphate (PRP. With buffer that did contain detergent, antibodies to LPS were not detected, whereas detection of antibodies to the non-LPS somatic components and to PRP wa unimpeded. Similarly, purified LPS could be used as test antigen with the former buffer only. IgG, IgA, and IgM antibodies to non-LPS somatic antigens were prevalent in healthy adults and children, and levels increased in 14 of 15 patients recovering from meningitis due to H. influenzae type b; IgG was the predominant class. Antibodies to LPS were prevalent but at lower concentrations, and IgM was the predominant class; levels increased in 12 of the 15 patients.