Serum antibody response to Bacteroides fragilis in experimental sinusitis.

Maxillary sinusitis was induced in New Zealand white rabbits by local inoculation of 10(6) colony-forming units of Bacteroides fragilis NCTC 9343, and the serum IgG, IgA and IgM antibody responses to cell wall antigens were studied. Prior to inoculation, and one, two, three and four weeks after induction, serum samples were obtained and analysed for antibodies to the lipopolysaccharide and the capsular polysaccharide. Capsular polysaccharide from B. fragilis ATCC 23745 was used as control. The rise in IgG activity against NCTC 9343 capsular polysaccharide and lipopolysaccharide was most marked and sustained throughout the four weeks. The increases in IgA concentration were moderate and sometimes transient, and a more pronounced IgA increase was seen with IFA than with EIA. The IgM peak levels were weak and usually declined within two to three weeks. The development of antibody to the lipopolysaccharide was similar to that of the NCTC 9343 capsular polysaccharide antibodies, though somewhat delayed in time. No significant increase in antibody to the control capsular polysaccharide was seen.