Hyperimmune human ABO blood-typing sera: reactivity with murine laminin and cytotoxicity for metastatic murine tumour cells.

Commercially prepared ABO blood-typing antisera have been tested for their ability to bind to murine laminin and their cytotoxic effects upon high and low metastatic variants of a murine fibrosarcoma. Previous studies have shown that alpha-D-galactopyranosyl end-groups comprise the major antigenic determinants on type B erythrocytes and that these same end-groups are present on murine laminin purified from the EHS sarcoma and on a laminin-like glycoprotein on the surface of the high, but not low, metastatic fibrosarcoma cells. In the present study we found that all sera containing anti-B activity were cytotoxic to the high, but not the low, metastatic cells and that all of these sera reacted strongly against immobilized murine laminin in an enzyme-linked immunosorbent assay. Sera lacking anti-B activity, i.e. anti-A antisera, were much less cytotoxic to either cell line and three of the four anti-A sera did not bind to murine laminin. The laminin reactivity and cytotoxic effect of the anti-B sera were specifically abrogated by preincubation of the sera with water-soluble blood group B substance or with murine laminin but not with water-soluble blood group A substance.