Blood group A/B-defined glycosyltransferase and A/B blood group antigens in human normal and malignant endometrium in relation to morphology,age and oestrogen levels

We have used monoclonal antibodies to study the expression and regulation of A/B antigens and A/B transferase in normal and malignant human endometrium by immunohistochemistry. Staining was evaluated against blood group status, morphology, age ad serum oestrogen levels. The expression of the antigens, in contrast tothe expression of the transferase, was related to the A subtype (A₁/A₂) and the ABH secretor status. Normal, non-secretory endometria and most well-differentiated endometrial carcinomas from ABH secretors expressed the antigens and the transferase, but showed a morphology-dependent variation in the expression and degree of coexpression. n contrast, most grade 2 and 3 carcinomas were found to lack both structures, whereas secretory endometrium had a high expression of the transferase but expressed the antigens on only a few cells. The transferase expression was correlated inversely with age and positively with the level of free oestradiol in serum. Our findings suggest that A/B antigenic expression in the endometrium may be regulated at different levels — at the A/B transferase level and at a precursor substrate lvel — and that both genetic and hormonal factors are probably involved in the regulatory process.