ENHANCED PRODUCTION OF B-LYMPHOCYTES AFTER CASTRATION

Castration has long been recognized to stimulate thymic growth and augment cellular immunity. We sought to determine whether castration affects B lymphopoiesis by analyzing the phenotype of bone marrow and spleen cells from animals postcastration. In this report, we show that the bone marrow cells from castrated male mice show a sustained, twofold to threefold increase in numbers of B220(+)/IgM(-) cells and of newly formed B220(+)/IgM(+) B cells. Most of the expanded B220(+)/IgM(-) cell population consisted of small, HSA(hi), CD43(-) cells characteristic of pre-B cells. The castrated animals also showed increased numbers of splenic B cells, primarily consisting of small IgM(+), IgD(lo), B220(lo), HSA(hi) cells. Taken together, these results show that castration causes dramatic, long-lived enhancement of B lymphopoiesis in bone marrow and increased numbers of mature B cells in the periphery. (C) 1995 by The American Society of Hematology.