title: Regulation of constitutive bone marrow cell proliferation by bone marrow suppressor cells.
abstract: Bone marrow (BM) cells have previously been shown to suppress specific immune responses of cells from peripheral lymphoid organs. The present report describes a suppressor cell present in normal rabbit BM, which regulated the constitutive proliferation of other BM cells. The suppressor cells were Fc gamma-receptor-positive (Fc gamma R+) complement-receptor-negative, and nonadherent or weakly adherent. Similar suppressive activity was not detected among rabbit spleen cells. Removal of Fc gamma R+ suppressor cells allowed greater than 10-fold increases in the proliferation of Fc gamma R- BM cells. Addition of Fc gamma R+ BM cells to Fc gamma R- cells efficiently blocked proliferation. The suppressor cells acted by inhibiting the elaboration of a soluble growth-promoting factor by cells in the Fc gamma R- population. The growth-promoting factor enhanced proliferation of unseparated rabbit BM cells and peripheral blood mononuclear cells.
mesh_terms: D000818:Animals; D001854:Bone Marrow Cells; D002448:Cell Adhesion; D002455:Cell Division; D006131:Growth Inhibitors; D011817:Rabbits; D011951:Receptors, Complement; D011961:Receptors, Fc / Q000502:physiology; D017452:Receptors, IgG; D012995:Solubility; D050378:T-Lymphocytes, Regulatory / Q000276:immunology*
chemical_list: D006131:Growth Inhibitors; D011951:Receptors, Complement; D011961:Receptors, Fc; D017452:Receptors, IgG