[Spleen and hematopoiesis].

In order to investigate the role of the human spleen on hematopoiesis, hematopoietic stem cells and stimulates were evaluated in fetal and adult spleens. BFU-E and CFU-C were existed in 20 weeks and 23 weeks fetal spleens (BFU-E 145 +/- 45/10(5) mononuclear cells, CFU-C 55 +/- 6/10(5) mononuclear cells). In adult spleen, a few stem cells were recognized, which may be contaminated from peripheral blood in sinus of the spleen. We tested conditioned media from adult spleen cells for the stimulative activity on the in vitro growth of BFU-E and CFU-C from bone marrow mononuclear cells. Spleen conditioned medium stimulated proliferation of these precursor cells. It seemed that PHA-stimulated spleen conditioned medium augmented BFU-E, whereas CFU-C growth was suppressed. Adult and fetal spleens were studied immunohistochemically using anti-G-CSF, GM- CSF and erythropoietin antibodies. The cells with G-CSF and GM-CSF were shown in fetal spleens. In adult spleens, however, only GM-CSF was detected.