Immunohistochemical localization in rat gastrointestinal tract of a sialomucin species recognized by HCM31, a new anti-mucin monoclonal antibody

It has been recognized that distinct mucus secreting cells of the gastrointestinal tract express specific type of mucins. We have recently demonstrated that a kind of sialomucin specifically stained with a monoclonal antibody (mAb) HCM31 is temporarily and specifically expressed in the mucous cells regenerated from acetic acid-induced gastric damage in rats. The aim of this study was to immunohistochemically characterize the distribution of the specific type of sialomucins recognized by this mAb throughout the digestive tract and age-dependent alteration of this expression in rats. The gastrointestinal tracts of eight-week-old and eighty-eight-week-old male Sprague Dawley rats were used in this study. In both young and aged rats, HCM31 reacted with the surface mucous cells of the cardiac gland, recognizable as 2 or 3 pits adjacent to the forestomach. The goblet cells in the duodenum, jejunum, ileum, cecum and proximal colon were also stained with HCM31. In the young rat, epithelial cells including the goblet cells in the distal colon and the rectum were not stained with HCM31. On the other hand, the goblet cells in the distal colon and rectum of the aged rats were stained positively with HCM31. These findings indicate that the immunohistochemical observations using this mAb, as well as other anti-mucin mAbs developed by us, should be very useful for the evaluation of changes in the mucin species with respect to the physiological and pathological alterations in the alimentary tract of rats.