Anti-A haemagglutinins in factor VIII concentrates.

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 redissolved. From a practical point of view, factor VIII concentrates prepared from cryoprecipitate obtained from single donations of plasma unselected for ABO group contain significantly less anti-A than those prepared from mixing pools of plasma in which partial neutralisation of anti-A has occurred before cryoprecipitation.