Antibody response of patients with Helicobacter pylori-related gastric adenocarcinoma: significance of anti-cagA antibodies

Abstract

The aim of this study was to search for a specific antibody pattern in sera from patients suffering from Helicobacter pylori-related gastric adenocarcinoma (GAC). The serological response of 22 patients suffering from GAC, 31 patients with gastroduodenal ulcer, and 39 asymptomatic subjects was analyzed using immunoblotting performed with three H. pylori strains: strain ATCC 43579; strain B110, isolated from a patient with ulcers; and strain B225, isolated from a patient with GAC. In addition, the latex agglutination test Pyloriset Dry was used to analyze ambiguous sera. H. pylori seropositivity was 75% in the GAC group, 61.3% in the ulcer group, and 56.4% in the asymptomatic group. Anti-CagA antibodies were found more often in the GAC group (48.8%) and in the ulcer group (47.3%) than in the asymptomatic group (21.2%). These percentages depended on the strain used as an antigen: in the GAC group, the anti-CagA frequencies were 93.3, 40, and 13.3% with strains B225, B110, and ATCC 43579, respectively. Thus the presence of anti-CagA antibodies was increased in patients suffering from H. pylori-related GAC, in particular when the CagA antigen was from a GAC strain. These data suggest the existence of a CagA protein specifically expressed by H. pylori strains isolated from GAC patients.

FIG. 1

Electrophoretic profiles of the saline extracts prepared from the three H. pylori strains: B110 (lane 1), B225 (lane 2), and ATCC 43759 (lane 3). Proteins were resolved in a 12% acrylamide gel and silver stained. MW, molecular weight markers in thousands.

FIG. 2

Variability of the immunoblots obtained with one seronegative patient (A) and one seropositive patient (B) according to the three H. pylori stains used as antigens: B110 (lanes 1), B225 (lanes 2), and ATCC 43759 (lanes 3).

FIG. 3

Mean frequencies (as percentages) of the 10 immunoreactive bands detected by immunoblot assay in the sera of 56 seropositive subjects (columns in black) and the 34 seronegative subjects (columns in grey). Antibodies were directed to CagA (columns 1), VacA (columns 2), fumarate reductase (columns 3), UreB (columns 4), HspB (columns 5), catalase (columns 6), p35 (columns 7), UreA (columns 8), p26 (columns 9), and ferritin like protein (columns 10).

FIG. 4

Factorial analysis of correspondence of the 90 immunoblots performed with strain B110. ■, projection of the 34 seronegative subjects; ●, projection of the 56 seropositive subjects.

FIG. 5

Frequency (as percentages) of anti-CagA antibody in the three groups according to the H. pylori strain used as an antigen to perform the immunoblots.