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.