Gastric cancer progression associated with local humoral immune responses

BACKGROUND: Although the association between H. pylori and gastric cancer has been well described, the alterations studies are scarce in the humoral immune response in specific anatomical areas of stomach and during the stages of gastric cancer. The aim in this study was to determine the influence of humoral immune responses against H. pylori infection on gastric carcinoma. METHODS: We selected 16 gastric cancer cases and approximately one matched control per case at the National Institute of Medical Sciences and Nutrition Salvador Zubirán (INCMNSZ); all the cases met the inclusion criteria for the study. We obtained three biopsies from each patient and from each of the predetermined regions of the stomach: antrum, angular portion, corpus, and fundus. From the patients with gastric cancer, additional biopsy specimens were obtained from tumor mid-lesion and tumor margin, and additional specimens were collected at least 2 and 5 cm from the tumor margin. We compared IgA levels against H. pylori in each area of stomach between cases and controls as well as between early and advanced stages of gastric cancer. RESULTS: IgA values were strikingly elevated in cancer cases compared with control subjects; a value that was even higher in the distant periphery of tumor but was remarkably decreased toward the carcinoma lesion. The advanced stages of gastric cancer demonstrated the relapse of the humoral immune response in the mid-lesion region of the tumor compared with the tumor margins and adjacent non-tumor tissue. CONCLUSIONS: Gastric cancer is characterized by progressive accumulation of a concentrated, specific IgA response against H. pylori, beginning with an abnormal increase in the entire stomach but particularly in the adjacent non-tumor tissue. Thus, it is possible that this strong immune response also participates in some degree in the damage and in the development of gastric cancer to some extent.