Studies on antibody production. V. The secondary response in vitro.

Rabbits were injected into the hind foot with diphtheria toxoid and bovine serum albumin. Fragments of popliteal lymph node taken from them several months later were placed in plasma-clot cultures with Eagle's medium. When antigen was added to the culture fluid, anamnestic antibody responses occurred regularly. When the antigen was diphtheria, responsiveness remained for 4 days after the beginning of the culture. When it was bovine serum albumin, responsiveness lasted for about 8 days. Once an anamnestic response had begun, antibody formation continued for 4 weeks or more. High concentrations of bovine serum albumin (0.5 mg/ml) did not inhibit the response. When both antigens were used to stimulate the same culture, it was found that the two responses were independent.