Receptor - Specific Inhibition of Bone Marrow

lnterleukin-2 (IL-2) induces differential secretion of lymphokines by li-2 receptor (li-2R)-positive and lL-2Rnegative T cells. We studied T cell lL-2R-specific modulation of adult bone marrow erythropoiesis by recombinant lL-2 (rli-2). li-2R were induced by CD3 T cell surface determinant-triggering and analyzed by cytofluorography. Bone marrow monocyte and T cell-depleted (NAB-T) target cells were assessed for early erythroid progenitor expression (BFU-E) in the presence of 0 to iO U/mi of rli-2. rli-2 had no significant effect on BFU-E expression in the absence of T cells or in the presence of lL-2R-negative T cells. rli-2 caused a dose-dependent inhibition (75% to 90%) of BFU-E in the presence of autologous lL-2R-positive T cells. The addition of anti-l12-receptor antibody to cultures containing rli-2 plus lL-2R-positive T cells entirely abrogated rli-2-mediated inhibition of BFU-E. In the pres-