The importance of Ludwik Hirszfeld's contributions to our knowledge of the ABO blood group system has been affirmed in various ways: by Karl Landsteiner (1931) in his Nobel Address, by Hirszfeld's election to the Presidency of the Blood Group Section of the Second International Congress of Blood Transfusion (Paris, 1937), and by the naming in his memory of the Hirszfeld Microbiological Institut...

The incidence of maternal Rh immunization in Rh-negative women following a single ABO compatible Rh-positive pregnancy is about 17%. This incidence was determined by following Rh-negative women through two Rh-incompatible pregnancies and analysing their sera for anti-Rh at the time of delivery of their second observed pregnancy. Maternal Rh immunization occurs almost exclusively after delivery;...

Experimental evidence has been obtained that cryoprecipitation concentrates anti-A in mixtures of group O and group A plasma by a mechanism that does not operate in group O plasma alone. It has been concluded that the anti-A/A polysaccharide complex is less soluble during cryoprecipitation than anti-A immunoglobulin, and this complex dissociates to give free anti-A when the cryoprecipitate is r...