The Early Phase of the Antibody Response

Summary Spleen fragments from both primarily and secondarily injected rabbits produced antibody to protein antigens when cultured in a suitable medium. The longer the antigen remained in vivo, the higher were the antibody titers in extracts and in cultured material. The antibody produced was specifically neutralized by the homologous antigen. Antibody synthesis seemed to occur intracellularly with little or no induction phase, with release into the surrounding medium occurring at a later time. The titers of culture fluids and serums were shown to be about 8-fold higher when S. typhosa endotoxin was given 24 hr in advance of the primary antigen injection, but not when the endotoxin was given simultaneously with the antigen. In both cases, spleens were removed 2 hr after antigen injection.