Immunohistochemical detection of gastric mucin in normal and disease states

At least seven human mucin genes have been described, which express glycoproteins MUC1-7 in various tissues. It has been shown that different mucins are expressed in various gastric disease states compared to the normal. In this study we used histochemical and immunohistochemical methods to determine the type and pattern of mucin in 54 patients with a variety of gastric conditions [i.e., normal controls, fetal stomachs, gastritis, low-grade dysplasia, intestinal metaplasia (associated with gastritis, benign ulcers, dysplasia, and cancer), early and advanced intestinal type adenocarcinoma, and diffuse adenocarcinoma]. We report for the first time the use of all seven MUC antibodies in the various conditions. Normal controls were immunoreactive for MUC4, 5, and 6 , and gastritis specimens showed similar results, although the latter showed more MUC1 immunoreactivity. Whereas early fetal stomach showed no MUC immunoreactivity, MUC4, 5, and 6 were present from the early second trimester onwards. There was no significant difference between dysplasia and intestinal metaplasia, both categories showing the presence of MUC2 and 3 predominantly. Early intestinal type adenocarcinomas did not show any mucins in the majority of cases. Advanced intestinal type adenocarcinomas showed immunoreactivity predominantly for MUC1, 5, and 6, as well as MUC2 in some cases. Diffuse adenocarcinomas showed strong positive MUC2 and 6 staining, and in some cases MUC5 and 7. In conclusion, we have shown different patterns of mucin immunoreactivity in various gastric disease states. Specimens with dysplasia, intestinal metaplasia, late intestinal type adenocarcinoma, and diffuse gastric cancer were characterized by increased diversity of mucin types, whereas early intestinal cancer showed loss of mucin immunoreactivity.