Antibody-dependent cellular cytotoxicity (ADCC) in colorectal carcinoma. II. Blood group association.

Colorectal carcinoma patients' sera with ADCC antibody reacting with the HT-29 cell line (blood group A) generally (88%) cross-reacted with another group A cell line (COLO-394) but much less frequently (6-33%), with six tumor cell lines that did not express ABO blood group antigens. The findings suggested the possibility that the ADCC reactivity against the HT-29 cell line particularly by patients of blood group O is generally via "A" or "A-like" antigenicity of the target cells. This was supported by absorption studies that showed that the ADCC reactivity could be removed by blood group A but never by group B erythrocytes. Our results suggest that the prognostically favorable ADCC antibody in colorectal carcinoma patients' sera is of anti-blood group A specificity or cross reactivity.