Serum antibody responses to the N-acetylneuraminyllactose-binding hemagglutinin of Campylobacter pylori.

We recently reported that Campylobacter pylori possesses a surface-associated fibrillar hemagglutinin which has an affinity for N-acetylneuraminyllactose; this hemagglutinin may function as a colonization factor for attachment to the gastric epithelium. In the present study we examined serum samples obtained from 65 C. pylori-infected individuals with gastric ulcers, duodenal ulcers, or both and from 121 asymptomatic volunteers, including 62 who were infected with C. pylori, for immunoglobulin G (IgG) specific for the C. pylori neuramin-lactose-binding hemagglutinin (NLBH). The NLBH purified from a single isolate was used as the antigen in an enzyme-linked immunosorbent assay. A positive result was obtained with serum from 81.5% (53 of 65) of the individuals with ulcers, 67.7% (42 of 62) of the C. pylori-infected volunteers, and 1.7% (1 of 59) of the C. pylori-negative volunteers. This result confirms that NLBH is produced in vivo. There are several possible explanations for the fact that only 75% of 127 C. pylori-infected individuals were positive for anti-NLBH IgG in serum. We favor the hypothesis that there are probably several antigenically distinct C. pylori NLBHs, i.e., NLBHs which would stimulate antibody that was undetectable by the antigen used in the enzyme-linked immunosorbent assay described here.