[Phenotyping Kell and Duffy antigens by a technic of coagglutination on the Groupamatic G 360]

By adapting the technique of coagglutination to the Groupamatic, we have developed an efficient rapid method of phenotyping donors for the Kell and Fya antigens. 340 specimens can be tested per hour; 800 tests can be performed with only 15 ml of antisera. Over 10,000 donor specimens were tested for Kell and 2,470 were simultaneously phenotyped for Fya. No false negatives were observed. The rate, of false positive results, due to autoagglutinins coating the donors' red cells, was the same as that seen with the continuous flow method. We conclude that this technique is suitable for routine use in screening donors for Kell and Fya antigens.