Influence of antigen dose on antibody production of intact and splenectomised Xenopus laevis.

Antigen persistence and serum antibody production in intact Xenopus were monitored using human gamma globulin (HGG), in adjuvant, in various immunisation schedules. Retention of HGG in spleen and serum was directly related to the quantity injected. However, antibody responses to a dose range between 1 mu-g-6 mg antigen were similar in intensity. These were detected in the serum two weeks after injection and at this stage were exclusively mercapto-ethanol (ME) sensitive; ME-resistant antibodies had appeared by four weeks. No antibodies were detected below a dose of 100 ng HGG. The effect of splenectomy on antibody levels was tested using HGG/adjuvant or sheep erythrocytes (SRBC) in saline. Splenectomised toads showed impairment of antibody responses only to threshold doses of HGG (100 ng) but to a wider range of SRBC doses.