INHIBITION OF MURINE B-LYMPHOPOIESIS AND T-LYMPHOPOIESIS INVIVO BY ANANTI-INTERLEUKIN-7 MONOCLONAL-ANTIBODY

The effects of interleukin 7 (IL-7) on the growth and differentiation of murine B cell progenitors has been well characterized using in vitr o culture methods. We have investigated the role of IL-7 in vivo using a monoclonal antibody that neutralizes IL-7. We find that treatment o f mice with this antibody completely inhibits the development of B cel l progenitors from the pro-B cell stage forward. We also provide evide nce that all peripheral B cells, including those of the B-1 and conven tional lineages, are derived from IL-7-dependent precursors. The resul ts are consistent with the rapid turnover of B cell progenitors in the marrow, but a slow turnover of mature B cells in the periphery. In ad dition to effects on B cell development, anti-IL-7 treatment substanti ally reduced thymus cellularity, affecting all major thymic subpopulat ions.