Mucin-type carbohydrates (type 3 chain antigens) in normal cycling human endometrium

Carbohydrates related to the ABO, Tn, and T blood group systems are markers of cellular differentiation in many epithelial tissues. Using a panel of specific monoclonal antibodies, we have immunohistochemically investigated the expression of mucin-type (type 3 chain ABO-related) antigens in 64 samples of normal cycling endometria of known ABO and Lewis blood type. Tn and T antigens had a highly restricted expression in normal cycling endometrial tissue. The expression of type 3 chain H and A antigens was always compatible with the ABO blood type of the individual and seems to be regulated by the secretor genes, as secretors [Lewis (a-b+)] expressed more A and H type 3 chains than nonsecretors [Lewis (a+b-)]. The expression of type 3 chain H and A, sialyl-Tn and sialyl-T antigens showed cyclic variations in the glandular epithelium of the functionalis, but not of the basalis layer of cycling endometrium. A hormonal regulation of the enzymes involved in blood group-related carbohydrate chain elongation in human endometrium is thus possible and may participate in the specialized secretory process of human cycling endometrium.