SEROLOGICAL ASSESSMENT OF THE EARLY RESPONSE TO ERADICATION THERAPY USING AN IMMUNODOMINANT OUTER-MEMBRANE PROTEIN OF HELICOBACTER-PYLORI

Eradication of Helicobacter pylori infection cures gastritis and preve nts recurrence of peptic ulcers, Endoscopy is usually used to evaluate the effectiveness of eradication therapy. We designed a new noninvasi ve assay system for the early evaluation of eradication of H. pylori i nfection in which a crude H. pylori outer membrane protein preparation (HPOmp) is used as an antigen, and we determined the sensitivity and specificity of the serological assay system. Immunoblot analysis showe d that anti-HPOmp antibodies reacted to a protein with a molecular mas s of approximately 29 kDa. In those patients who responded to therapy the anti-HPOmp immunoglobulin G (IgG) titers measured by enzyme-linked immunosorbent assay (ELISA) at 1 month after the end of therapy were significantly lower than those before treatment (34.8% reduction; P < 0.001), and the posttreatment reduction in the antibody titer was sign ificantly greater than that of the titer measured with a commercially available anti-H. pylori IgG ELISA (34.8% versus 16.1%; P < 0.001). Wh en a 25% reduction pf anti-HPOmp IgG titer at 1 month after the end of treatment was taken as the cutoff value for H. pylori eradication, th e sensitivity and specificity of our new assay were 75% (51 of 68 trea tment responders) and 96% (22 of 23 nonresponders), respectively. Our results indicate that the novel serological test with HPOmp might be a clinically useful tool for assessment of eradication of H. pylori.