Tolerance induction to cultured islet allografts. II. The status of antidonor reactivity in tolerant animals.
Murine islet tissue cultured in 95% O2 to eliminate/inactivate donor antigen-presenting cells can function indefinitely and induce a state of tolerance in nonimmunosuppressed, allogeneic recipients. Such cultured grafts represent a model of antigen presentation in which antigen (signal 1) is presented without the delivery of appropriate costimulatory activity (signal 2) necessary for T cell activation. As T cell inactivation has been proposed to result from this form of antigen presentation, we determined whether the tolerance generated in response to such cultured grafts was due to a passive (clonal deletion/inactivation) mechanism. We have shown that, although tolerant in vivo, animals bearing long-term cultured islet allografts are donor-reactive in vitro as assessed by (1) CTL precursor frequency, (2) antidonor proliferative and cytotoxic responses, and (3) lymphokine production (IL-2, IL-3, TNF, and IFN-gamma). In addition, tolerance does not appear to be tissue (islet)-specific in that primed, donor-reactive T cells from tolerant animals react to islet cells in vitro and are capable of destroying donor-type islet grafts in vivo. Thus, the notion that "signal 1" antigen presentation, as represented by cultured islet allografts, leads to the clonal deletion or inactivation (anergy) of donor-reactive T cells is not supported by these results. Since this form of tolerance does not appear to be an intrinsic property of the donor-specific lymphocyte, these results are more consistent with a model of active regulatory tolerance in vivo.
Coulombe
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M
Barbara Davis Center for Childhood Diabetes/University of Colorado Health Sciences Center, Denver 80262.
Gill
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RG
D000818:Animals; D000938:Antigen-Presenting Cells / Q000276:immunology; D002478:Cells, Cultured; D006082:Graft Enhancement, Immunologic; D006084:Graft Rejection / Q000276:immunology / Q000517:prevention & control; D015395:Histocompatibility Antigens Class I / Q000276:immunology; D007108:Immune Tolerance; D016381:Islets of Langerhans Transplantation / Q000276:immunology*; D008213:Lymphocyte Activation; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008808:Mice, Inbred CBA; D016513:Mice, SCID; D011948:Receptors, Antigen, T-Cell / Q000276:immunology; D013601:T-Lymphocytes / Q000276:immunology
D015395:Histocompatibility Antigens Class I; D011948:Receptors, Antigen, T-Cell