Histological differentiation and basement membrane distribution in gastric adenocarcinomas

To analyse the histological distribution of basement membranes (BM) in gastric adenocarcinomas, we produced a monoclonal antibody, BM909 (IgG 2b, kappa), which has been found useful for identifying the BM in routinely processed specimens. The BM 909 antibody was shown by ELISA to be negative against the three major BM components (type IV collagen, laminin and fibronectin). Gastric carcinomas from 78 patients including both differentiated and undifferentiated adenocarcinomas were classified into three types (tubular, trabecular, and isolated) based on the histological arrangement of the cancer cells. Histological distributions of the BM were also classified into four patterns (peritubular, peritrabecular, intratrabecular, and pericellular) based on the immunostaining results with the BM 909 antibody. Our results demonstrated a close relationship between these two parameters as follows: 1) the tubular type of gastric carcinomas showed a peritubular pattern of BM distribution in the differentiated adenocarcinomas; 2) The isolated type of gastric carcinomas showed a pericellular pattern of BM distribution in the undifferentiated adenocarcinomas; and 3) The trabecular type of gastric carcinomas showed either peritrabecular or intratrabecular patterns of BM distribution, in both differentiated and undifferentiated adenocarcinomas. In conclusion, we suggest that all gastric adenocarcinomas are accompanied by BM deposition regardless of the degree of histological differentiation.