The role of macrophages and T-lymphocytes in glucan-mediated alteration of murine hemopoiesis.

We have investigated the mechanism of glucan-mediated increase of splenic (SPL) and decrease of bone marrow (BM) hemopoiesis in B6DF1 mice. To determine the involvement of macrophages in these phenomena, B6DF1 mice were treated with silica 24 hrs prior to glucan injection and then tested for BM and SPL CFU-GM and CFU-S activities. Silica treatment reduced significantly augmentation of SPL, but not the decrease of BM CFU-GM proliferation, indicating that the former phenomenon is macrophage dependent, whereas the latter is not. Since no change in BM or SPL CFU-S proliferation was observed after silica treatment, it appears that macrophages are not involved in glucan-caused alterations of CFU-S. Athymic mice (not possessing mature T cell functions) also exhibited decreased BM and increased SPL CFU-GM proliferation after glucan treatment; however, the SPL CFU-GM augmentation in athymic mice was not as dramatic. Hence, although glucan's action did not appear to be completely dependent on mature T-cells, these cells appear in some way to act with macrophages to enhance the proliferation of SPL CFU-GM after glucan treatment.