[Hemolyzing antibodies to markers of the P blood factor system as a problem in blood transfusion and pregnancy. With reference to serology, biochemistry and genetics].

The extremely rare phenotypes p, P1k and P2k (0.0005-0.0006%) of the blood group P system are usually found in consanguinous families. In the serum of these persons haemolytic antibodies with the specificity anti-PP1Pk and anti-P are found, causing severe haemolytic reactions after transfusion of incompatible blood. Because of their rarity it is difficult to find compatible blood donors. The antibodies are also associated with abortion early in pregnancy. Since 1948 at the "Institut für Blutgruppenserologie der Universität Wien" 4 persons of the phenotype p and 3 of the type P2k were observed in altogether 5 families. Two of them needed blood transfusions, the one p patient received p blood from her sister, who likewise gave blood to the other p patient. This latter patient additionally received three blood units which had been stored in liquid nitrogen and came from Austria and from the European bank of frozen blood in Amsterdam (Council of Europe). The pedigrees of three families with 5 probands out of the 7 observed cases could be reconstructed and showed consanguinity, partly some generations back. A genetic model valid at the moment for the biosynthetic pathway of the P antigens is demonstrated and the appropriate serological characteristics of the haemolytic antibodies are shown. The seven antibodies are partly IgG and partly IgM antibodies, optimally reacting using the indirect antiglobulin test or enzyme-treated red cells. The range of the antibody titres was between 1:8 and 1:1024. Absorption of Anti-PP1Pk sera with red cells of type P1 to get Anti-Pk and inhibition with hydatidcyst fluid and globoside to receive Anti-P and Anti-P1 + Pk, respectively were partly successful.