Inhibitory signals from thymic stromal cells can counteract B lymphopoietic stimuli.

(A) The experimental protocol used to introduce transwells containing heterogeneous BM or thymic stromal cells into myeloid (Dexter) long-term BM cultures at the time of their transfer to B-lymphoid permissive conditions. (B) Nonadherent cells were harvested weekly from the cultures and analyzed for expression of CD45R. Data are representative of 3 experiments.