Abstract
A, B and H(O) [human] blood group antigens in some tissues are readily demonstrable by the specific red cell adherence test (SRCA) which is a modification of Coombs'' mixed cell adherence technique. Paraffin-embedded tissue sections obtained from tumors of the urinary bladder were submitted to SRCA. Normal bladder epithelium adjacent to neoplastic lesions and the leukoplakia contained the 3 antigens. The antigens were completely absent in 18 cases and partially present in 1 bladder carcinoma. The prognosis of the tumor apparently correlates with the antigen loss. SRCA is sensitive, reproducible and technically easy for detection of tissue antigens, and it would be expected to play a crucial role for demonstration of immunological dedifferentiation in tissues which normally keep the antigens.