Fetal gastric and small intestine pattern of intestinal mucus antigens in human gastric carcinomas.

The present immunohistological study was performed to investigate the expression of intestinal mucus-associated antigens in the different histological types of gastric carcinoma according to the classification of Laurèn and the WHO classification. We used the following antigenic markers: M3, present in all the goblet cells of the whole small and large intestine; M3SI, expressed in all the goblet cells of the small intestine, but only in some of them of the large intestine; M3D, mainly produced in the upper small intestine; and M3C, specific for colonic mucus cells. All these antigens were found to be similarly expressed in both Laurèn's intestinal and diffuse types. Nevertheless, M3 and M3C appeared to be more largely produced in carcinomas showing well-differentiated cells (tubulopapillary, mucinous, and signet ring cells according to the WHO classification). Our results evidenced the occurrence of two main fetal antigenic patterns in gastric carcinomas, one of the gastric type (M3SI produced to a larger extent than M3 and M3C) and the other one of the small intestinal type (M3 and M3SI more largely expressed than M3C). On the basis of their similar antigenic pattern, the histogenesis of carcinomas showing the fetal small intestinal antigenic profile may be associated with intestinal metaplasia. On the other hand, carcinomas with the fetal gastric pattern may originate from undifferentiated stem cells of the gastric mucosa. Thus, such immunohistological studies could lead to a better understanding of the histogenesis of gastric carcinomas.