CagA and VacA are immunoblot markers of past Helicobacter pylori infection in atrophic body gastritis.
OBJECTIVE
Atrophic body gastritis (ABG) may be induced by H. pylori infection. It is difficult to diagnose H. pylori infection in this condition, since during progression of body atrophy the bacterium disappears. In 30% of patients with ABG no sign of H. pylori infection is detectable. We aimed to investigate whether patients with ABG, classified as H. pylori-negative by conventional methods (ELISA serology and Giemsa stain histology), have been previously exposed to the infection.


METHODS
Case series consisted of 138 outpatients with ABG, of whom 31 are H. pylori negative (histology and ELISA serology), and 107 are H. pylori related (histology and ELISA serology positive: active infection, n = 29; only serology positive: past infection, n = 78). Thirty control subjects who were H. pylori negative at histology and ELISA serology were investigated. Immunoblotting of sera against H. pylori whole-cell protein lysate was performed.


RESULTS
None of the control sera recognized CagA, VacA, heat-shock protein B, and urease B, yielding a specificity of 100%. All H. pylori-negative patients with ABG showed immunoblotting seroreactivity, including in each case either CagA or VacA. The concomitant seroreactivity against CagA and VacA was highly prevalent in the H. pylori-negative patients with ABG, comparable to those with active infection (77.4% vs. 86.2%) and with past infection (vs. 61.5%).


CONCLUSIONS
Immunoblotting against CagA and VacA is able to prove past exposure to H. pylori infection in all patients with ABG defined as H. pylori-negative by conventional methods, suggesting a hidden role of H. pylori infection in gastric atrophy also in these patients.
Annibale
Bruno
B
Department of Digestive and Liver Disease, University La Sapienza, Ospedale Sant'Andrea, Rome, Italy. bruno.annibale@uniroma1.it
Lahner
Edith
E
Santucci
Annalisa
A
Vaira
Dino
D
Pasquali
Amelia
A
Severi
Carola
C
Mini
Roberta
R
Figura
Natale
N
Delle Fave
Gianfranco
G
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000907:Antibodies, Bacterial / Q000097:blood*; D000942:Antigens, Bacterial / Q000276:immunology*; D001426:Bacterial Proteins / Q000276:immunology*; D015415:Biomarkers / Q000097:blood*; D005260:Female; D005757:Gastritis, Atrophic / Q000209:etiology*; D016481:Helicobacter Infections / Q000097:blood / Q000150:complications* / Q000175:diagnosis; D016480:Helicobacter pylori / Q000276:immunology*; D006801:Humans; D015151:Immunoblotting; D008297:Male; D008875:Middle Aged; D012698:Serologic Tests
D000907:Antibodies, Bacterial; D000942:Antigens, Bacterial; D001426:Bacterial Proteins; D015415:Biomarkers; C074689:VacA protein, Helicobacter pylori; C080866:cagA protein, Helicobacter pylori