FAILURE OF LYMPHOPOIESIS AFTER ADOPTIVE TRANSFER OF NF-KAPPA-B-DEFICIENT FETAL LIVER-CELLS

Mice deficient in the p65 subunit of NF-kappa B die during fetal devel opment. Introduction of p50/p65-deficient fetal liver cells into letha lly irradiated hosts resulted in a severe deficit of fetal liver-deriv ed lymphocytes and their immediate precursors but an overabundance of fetal liver-derived granulocytes. Surprisingly, simultaneous transplan tation of wild-type bone marrow cells rescued the production of p50/p6 5-deficient lymphocytes. Expression of immunoglobulin kappa light chai ns on these rescued NF-kappa B-deficient B lymphocytes was normal. The se results suggest that while p50 and p65 do not regulate the maturati on of pre-B cells, NF-kappa B mediates the development or survival of an early lymphocyte precursor through regulation of an extracellular f actor.