Biological Properties of the Cross-Reactions between Anti-BSA and Heterologous Albumins

Summary The in vivo reaction between rabbit anti-BSA and cross-reacting serum albumins produced systemic anaphylaxis, passive cutaneous anaphylaxis, and the Arthus phenomenon. In some situations, the biological effects produced by the cross-reactions were comparable to the biological effects produced by the homologous reaction, provided that the amount of cross-reacting antibody involved in the cross-reactions was the same as the amount of antibody involved in the homologous reactions. To obtain biological effects with the cross-reactions of severity comparable to the effects obtained with the homologous reaction, larger amounts of the cross-reacting antigens were required than of the homologous antigen. As judged by the in vitro and in vivo properties of the BSA-anti-BSA reaction and the cross-reactions, it appeared that the cross-reactions were usually less avid than the homologous reaction.