Distribution of blood group antigens A, B, H, and I(Ma) in mucus-producing adenocarcinoma of human lung.

The distribution of blood group antigens A, B, and H and their precursor antigen I(Ma) in the mucus of lung cancer patients was studied histochemically. Antigens A, B, and H compatible with the ABO status of the patients were expressed in the mucus of bronchial gland mucous cells and bronchial goblet cells except in a few patients presumed to be nonsecretors , while antigen I(Ma) was not expressed at all in these cells. In contrast, compatible antigens A, B, and H were decreased or not present in cancer cells but antigen I(Ma) accumulated. Accumulation of antigen I(Ma), which resulted from incomplete synthesis of antigens A, B, and H, was a tumor-associated phenomenon in the mucus of the lung and was found in all patients examined. However, the degree of this accumulation varied from patient to patient, and tumor cells showed marked heterogeneity even in an individual case. In addition, accumulation of antigen associated with loss of antigens A and B was demonstrated in cancer cell mucus of patients with a blood group status other than O. Expression of incompatible blood group antigen reactive with anti-A serum (A-like antigen) also was detected in cancer cell mucus of blood group B patients.