The Suppressive Effect of Supraoptimum Doses of Antigen of the Secondary Antibody-Forming Response of Spleen Cells Cultured in Cell-Impermeable Diffusion Chambers

Abstract

Summary The effect of antigen dose on adequately primed spleen cells was studied in cell-impermeable diffusion chambers. Maximum secondary antibody response against sheep red blood cells (RBC) was obtained when 1.2 × 107 spleen cells were cultured with 1.2 × 106 sheep RBC, a ratio of sheep RBC to spleen cells of 1:10. Maximum secondary antibody response against soluble bovine serum albumin (BSA) was obtained when 2.4 × 107 spleen cells were cultured with 50 µg of BSA. A suboptimum response was readily obtained not only by decreasing the antigen dose below the optimum but also by increasing it. Pulse-labeling studies with H3-thymidine were carried out during the log phase of response, when the total number of lymphoid cells remained relatively constant. The results revealed that antigenic stimulation can cause a twofold reduction in the t2 and therefore the t1/2 of the lymphoid cells from approximately 1.0 to 0.5 day. Further autoradiographic studies with use of H3-thymidine, H3-uridine and H3-proline revealed that morphologically distinct blast cells, lymphocytes and plasma cells are in general metabolically distinct, and the decrease in the t2 of the lymphoid cell population after antigenic stimulation is due to preferential proliferation of metabolically active blast cells and plasma cells. Furthermore they showed that the change in antibody output as affected by the dose of RBC antigen can be related mainly to the number of metabolically active plasma cells. Finally, immunofluorescent studies showed that when primed spleeen cells were cultured with over 100 times the optimum dose of BSA the number of functional antibody-forming cells decreased markedly 1 week after culture, and, in addition, the efficiency of these functional cells seemed to be reduced to one fourth of the normal. The significance of these results to the cytokinetics of antibody response is discussed.