The life cycle of antibody-forming cells. II. Evidence for steady state proliferation of direct haemolytic plaque-forming cells during the primary and secondary responses.

The nature of the proliferation kinetics of direct plaque-forming cells (PFC) was studied with an double isotope labelling method. The method measures and compares the cell fluxes crossing two different points in the cell-generation cycle. It could be shown with mathematical models that, in steady state proliferation, equal fluxes should be observed at all points of the cycle, and that, in exponential proliferation, unequal fluxes should be observed at all points.

The life cycle of antibody-forming cells. I. The generation time of 19S hemolytic plaque-forming cells during the primary and secondary responses.

The generation, time of cells synthesizing 19S antibody was measured during the exponential phase of the primary and secondary immune responses. Using a plaque-forming cell assay together with a double label isotope method, the duration of the generation time was found to be about 13 hr, that of the S period was about 8 hr, and that of G-1 and G-2 were about 3 and 2 hr, respectively, in both immune responses. Previous work was confirmed showing that all plaque-forming cells observed during the exponential phase of the immune responses incorporate labeled thymidine, and therefore take part in proliferation.