Assay of possible formation of antigenic components in heat-treated plasma protein preparations

To eliminate the risk of hepatitis infections, human plasma protein preparations can be heated in solution to 60 degrees C for 10 h thus inactivating several viruses. Preclinical safety experiments were performed in order to exclude the possibility of the formation of antigenic components, not present in normal human plasma, through this pasteurization step. Rabbits were immunized with either the heated or the unheated product. Sera were investigated in the Ouchterlony test against the homologous antigen to demonstrate precipitating antibodies. Antisera of rabbits immunized with the heated product were adsorbed with the preparation without the heating step. After centrifugation, the incubates were retested in the Ouchterlony assay. In passive cutaneous anaphylaxis assays guinea-pigs received the adsorbed antisera i.v., and both preparations were injected intracutaneously. The diameters of skin reactions were measured and did not show differences between those treated with the heated and non-heated product. No neoantigens could be detected with the following heated plasma protein fractions: prothrombin, coagulation factors VIII, IX, X, XIII, antithrombin III, fibrinogen, and Cl-inactivator. These results did not apply to heat-denaturated rabbit serum in a validation experiment.