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Background: The red cells of almost all human beings bear P antigen. Type P1 cells (around 75% of the population) contain P1 antigen in addition to P, and type P2 cells (around 25% of the population) contain only P. The red cells of only a few individuals are devoid of P: these cells may be of either Pk-positive (P1k and P2k[Pk]) or p type (the latter lack all the above-described antigens of the P system). Differentiation between them is of clinical importance, but there is a shortage of specific reagents. This article offers reliable means for differentiation., Study Design and Methods: Agglutination of washed, papain-treated red cells of all the P types by PA-1 and soybean lectins and adsorption of the lectins onto the red cells were examined., Results: PA-1 strongly agglutinated papain-treated red cells. Examination of its interactions with red cells having different P system antigens revealed that Pk (both P1k and P2k) red cells of O, A, and B blood types were agglutinated significantly faster than p red cells. The agglutination intensities of Pk red cells of types O and A (most people) was considerably stronger than those of p red cells. P1 and P2 type red cell agglutination was intermediate (P1>P2). Adsorption tests with all the red cells, exhibited the same order of PA-1 affinities for the P system blood types: Pk>P1,>P2>p. The soybean lectin exhibited opposite behavior (p>P2>P1>Pl)., Conclusion: The galactose-binding lectins PA-1 and soybean may facilitate the determination of Pk and p red cells.

A patient with postoperative intravascular hemolysis aggravated by transfusion with fresh whole blood and fresh plasma products had acute renal failure. Screening with Arachis hypogaea and Glycine soja lectins showed that his red cells were T-transformed. Only washed red cells were transfused subsequently, and no further fresh plasma products were given. All hemolysis ceased, the renal function returned to normal, and the T-polyagglutination as measured by lectin tests disappeared 4 months after surgery. Early diagnosis of polyagglutination using lectin screening tests is simple to perform, and will facilitate the immediate choice of the correct transfusion therapy, which in this case may have been life-saving.

A newborn infant of genotype P2p suffering from ABO-like hemolytic disease was born to a mother of the very rare genotype pp. The disease was severe enough to require exchange transfusions with pp blood. The mother and other members of the family with the same rare pp blood provided compatible donor blood for transfusions of the mother herself and for replacement transfusion of her affected infant. The mothers serum contained IgM molecules and also IgG molecules capable of crossing the placenta to induce a hemolytic process on the infant's red blood cells. The genotype of the P1 negative father was very likely P2P2 so that the genotype of the affected infant had to be P2p. A search of the literature revealed an earlier report from Japan in which the genotype of the P1 positive father was P1P2. As was to be expected the genotype of this affected infant was P2p.