Changes in bone marrow of treated and placebo animals.

Increased overall cellularity, increased percentage of T cells, and decreased number of megakaryocytes in the marrow of an IL-7–treated animal (B) compared with a placebo-treated animal (A) at the end of treatment (week 10). By week 14, the abnormalities observed in the same IL-7–treated animal at week 10 have abated (C). CD3 immunostain is shown in brown. CD4 and CD8 immunostains could not be performed due to a technical problem. Original magnification, × 80.