Selective activation of immunoregulatory T-cell circuits by an Ia+ antigen-presenting cell line.
ORA I-a, a cloned Ia+ monocyte tumor line, interacts with distinct immunoregulatory T-cell subsets. ORA cells present soluble and alloantigen to primed lymph node T cells and alloantigen to antigen-activated T-cell clones. However, they induce dose-dependent suppression during primary mixed lymphocyte cultures. Activation of a mixed lymphocyte response (MLR) suppressor pathway is mediated by Ly 1+ T cells. This T-cell subset proliferates in response to ORA when Ly 2+ cells are depleted. Furthermore, once activated, Ly 1+ T cells induce effectors of suppression within fresh T-cell populations. These studies indicate that antigen presentation to distinct T-cell subsets during different stages of an immune response may be mediated by unique antigen-presenting cell subpopulations. Immune homeostasis may thus be controlled not only by regulatory T cells, but also by unique antigen-presenting cells which are responsible for their selective activation.
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D000818:Animals; D000917:Antibody Formation; D000938:Antigen-Presenting Cells / Q000276:immunology*; D005260:Female; D000949:Histocompatibility Antigens Class II / Q000276:immunology*; D008213:Lymphocyte Activation; D007959:Lymphocyte Culture Test, Mixed; D051379:Mice; D008815:Mice, Inbred Strains; D013601:T-Lymphocytes / Q000276:immunology*
D000949:Histocompatibility Antigens Class II