Polyagglutinability associated with the cad antigen.

Various anti-Cad and anti-Sda reagents were tested against a panel of Cad red cells in order to determine whether Cad and Sda antigens were identical. According to the results, although strong Sda reactivity was always found in Cad red cells, the two antigen specificities are not identical. The polyagglutinability of Cad red cells seems to be related to an anti-Cad present in all human sera but Cad, and not with anti-Sda antibody.