[Immunofluorescent optical detection of HBSAG in the human small intestine in chronic aggressive HBSAG-seronegative hepatitis with diarrhea].

HBsAg has been detected by direct immunofluorescence in the small bowel biopsy specimen of a 16 a old male patient with diarrhoea and HBsAg seronegative (autoimmune) chronic aggressive hepatitis. HBsAg was localized focally in apical regions of intestinal crypts, in the cytoplasm, and on their cell membranes as well as in vascular endothelium. Pretreatment of the tissue sections with unlabelled anti-IgM, anti-IgG, and fresh human serum did not block the direct staining for HBsAg. Antisera to IgG, the complement components C1q, C4, and C5 as well as to fibrinogen and FITC-Staphylococcus protein A were bound in a similar manner. Therefore, it may be reasonable to assume, that hepatitis B virus can infect the human small intestine and could be regarded as one of rare gastroenteritic viruses.