The nature of antigen-antibody complexes formed in rabbits during an immune response to bovine serum albumin.

The immune elimination of soluble BSA, following an intravenous injection, is accompanied by the appearance of circulating antigen-antibody complexes. The pattern of the appearance of circulating antigen-antibody complexes and the immune elimination of antigen probably depends on the amount of antigen injected, the rate of antibody synthesis, and perhaps, the quality of antibody produced. There is no relationship between the I* antigen-antibody complexes detected during the immune response in rabbits by ammonium sulfate precipitation and the material precipitated from immune sera as a result of treatment with alkali. Alkali-precipitable material present in the serum of rabbits at a time when I* antigen is also present contain at most only traces of the antigen.