The immunohistological distribution of blood group (BG)-related antigens 
including A, B, H type 2, and sialylated Lex in lung adenocarcinomas was 
examined using monoclonal antibodies. BG-A, B, and H type 2 compatible with the 
ABO status in tumor cells were expressed in 60% of the cases. Accumulation of H 
type 2, associated with loss of BG-A and B, was observed in tumor cells of 
patients with BG status other than 0. Tumor-associated antigens, Lex and 
sialylated Lex were detected in 36.0% and 72.0%, respectively. Modification of 
carbohydrate antigens in cancer may be associated with incomplete synthesis; 
accumulation of precursor antigen; and activated sialylation.