B lymphocyte life span, rate of division and differentiation are regulated by total cell number.

I analyzed how B cell survival, the rate of B cell division and the rate of B cell activation may be affected in mice with different numbers of peripheral B cells. For this purpose, I created bone marrow (BM) chimeras with different BM B cell production; I analyzed peripheral B cell dynamics in these animals and studied the fate of carboxyfluorescein succinimidyl ester-labeled lymph node B cells transferred into these mice. I found that in lymphopenic mice, B cell life span is shortened and the rates of terminal B cell differentiation and cell death increased. As a consequence, I did not observe accumulation of B cells in mice with reduced but constant B-cell-poiesis. These results suggest that peripheral B cell survival relies not only on the number of competitors, as previously shown, but also on the rate of throughput of cells in a particular compartment.