IL-6 is an accessory signal in the alternative CD2-mediated pathway of T cell activation.
Recent studies have demonstrated that IL-1 and IL-6 are synergistic accessory signals for activation of T cells. In this study, highly purified human T cells were cultured with either a stimulating pair of anti-CD2 mAb or with immobilized anti-CD3 mAb. Monocytes, a cellfree monocyte culture supernatant or IL-1 were required for anti-CD2-stimulated T cell proliferation, and they each strongly enhanced anti-CD3-induced T cell growth. IL-6 was synergistic with IL-1 as a helper factor for T cell growth after activation via CD2, but we could not demonstrate any effect of IL-6 in the CD3 pathway. The mechanism of the synergistic helper activity of IL-1 and IL-6 on T cell activation in the CD2 pathway was further examined. IL-1 (but not IL-6) was required for induction of IL-2 production. Both IL-1 and IL-6 enhanced IL-2R (p55) expression and the proliferative response to IL-2. T cell proliferation after stimulation with anti-CD2 and IL-1 or IL-1/IL-6 proceeded through an autocrine IL-2-dependent pathway. Moreover we found that, in the absence of IL-1, IL-6 still supported a transient and limited proliferation of anti-CD2- (but not of anti-CD3-) stimulated T cells, which apparently was independent of the autocrine growth factors IL-2 or IL-4. Our data suggest that IL-6 is important as an accessory signal for T cell growth in the CD2 pathway of T cell activation.
Lorré
K
K
Department of Medicine and Pathophysiology, University of Leuven, Belgium.
Van Damme
J
J
Verwilghen
J
J
Baroja
M L
ML
Ceuppens
J L
JL
D000945:Antigens, Differentiation, T-Lymphocyte / Q000502:physiology*; D018801:CD2 Antigens; D017252:CD3 Complex; D004357:Drug Synergism; D006801:Humans; D066298:In Vitro Techniques; D007375:Interleukin-1 / Q000494:pharmacology; D007376:Interleukin-2 / Q000494:pharmacology; D015850:Interleukin-6 / Q000494:pharmacology / Q000502:physiology*; D008213:Lymphocyte Activation; D009000:Monocytes / Q000276:immunology; D011948:Receptors, Antigen, T-Cell / Q000502:physiology; D011971:Receptors, Immunologic / Q000502:physiology*; D015375:Receptors, Interleukin-2 / Q000502:physiology; D015398:Signal Transduction; D013601:T-Lymphocytes / Q000276:immunology*
D000945:Antigens, Differentiation, T-Lymphocyte; D018801:CD2 Antigens; D017252:CD3 Complex; D007375:Interleukin-1; D007376:Interleukin-2; D015850:Interleukin-6; D011948:Receptors, Antigen, T-Cell; D011971:Receptors, Immunologic; D015375:Receptors, Interleukin-2