title: Interleukin 2 induces proliferation of normal "resting" human T cells in the absence of other known external stimulation.
abstract: Interleukin 2(IL-2) is known to stimulate the progression of activated T cells from G1 through the rest of the cell cycle. We have demonstrated that addition of purified recombinant human IL-2 (rIL-2) to fresh normal human peripheral blood mononuclear cells (PBM), which were IL-2 receptor (Tac) negative by FACS analysis, stimulated marked proliferation of the PBM. IL-2-induced proliferation was also observed with umbilical cord blood mononuclear cells. Monocyte depletion of PBM resulted in a marked reduction of rIL-2-induced proliferative response which could be restored by adding back autologous irradiated monocytes but not by interleukin 1. The T cells preincubated with rIL-2 showed a five to six times enhanced autologous mixed-lymphocyte reaction (AMLR) compared to controls. The rIL-2-induced proliferative response of PBM was inhibited in a concentration-dependent fashion by preincubation of PBM with an anti-HLA-DR framework monoclonal antibody. The proliferating cells were shown by two-color flow cytometric analysis to be primarily Leu-1+ and Leu-4+ T cells (both leu-3+ and Leu-2+ subsets); however, 6 to 19% of responding cells had surface markers for B cells or NK cells. The data demonstrate that rIL-2 can induce proliferation of "resting" human T cells. The phenomenon may be related to a monocyte-dependent AMLR which induces IL-2 receptors and IL-2 responsiveness in a subset of T cells.
mesh_terms: D000328:Adult; D000911:Antibodies, Monoclonal; D002462:Cell Membrane / Q000276:immunology; D005260:Female; D005312:Fetal Blood / Q000166:cytology / Q000276:immunology; D006801:Humans; D066298:In Vitro Techniques; D007375:Interleukin-1 / Q000276:immunology; D007376:Interleukin-2 / Q000276:immunology*; D008213:Lymphocyte Activation; D007959:Lymphocyte Culture Test, Mixed; D008297:Male; D009000:Monocytes / Q000276:immunology; D013601:T-Lymphocytes / Q000276:immunology*
chemical_list: D000911:Antibodies, Monoclonal; D007375:Interleukin-1; D007376:Interleukin-2