[Cad antigen in the French population].
An investigation of Cad phenotypes in the French population had been carried out in 1973, in four Blood Transfusion Centers (Mulhouse, Nancy, Paris, Versailles), B and O red cells were tested with the Dolichos Biflorus lectin. Out of 78.528 donors, 56 were found to have the Cad antigen on their red cells. The mean frequency was 0,07%. Nevertheless, this frequency varied among the four above mentioned Blood Transfusion Centers: the observed differences were probably due to the preparation procedure of the Dolichos biflorus extract. The family investigation permitted the analysis of four families with at least three Cad individuals. The independence of the Cad system and of Auberger, Gc, Hp, C'3, PGM, Pac and ADA was demonstrated. A quantitative agglutination study on these Cad samples using the Dolichos biflorus lectin,and a selected AB serum showed a high variability of the erythrocyte Cad Strength, even within one family. Most Cad samples were found polyagglutinable when a sensitive technique and selected AB sera were used. All adult sera contained an anti-Cad1 antibody, except Cad1 individuals. Although strong Sda reactivity was always found in Cad red cells, the anti-Cad and anti Sda specificities were not identical: this was demonstrated by the absorption and inhibition tests of anti-Cad and anti-Sda reagents absorption and inhibition tests of anti-Cad and anti-Sda reagents with Sda material. From thf Cad red cells, there was no evidence of the existence of separable anti-A1 and anti-Cad agglutinins in the Dolichos biflorus lectin.