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Developmental Immunology
Volume 9 (2002), Issue 3, Pages 173-176
http://dx.doi.org/10.1080/1044667031000137656

Functional Tolerance is Maintained Despite Proliferation of CD4 T Cells after Encounter with Tissue-derived Antigen

Department of Pathology, University of California San Francisco, 513 Parnassus Avenue, San Francisco, CA 94143, USA

Copyright © 2002 Hindawi Publishing Corporation. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Since negative selection in the thymus is incomplete, some self-reactive T cells are able to mature and seed the periphery. To study how these T cells interact following encounter with the self-protein they recognize in the periphery, we have developed an adoptive transfer system in which HEL-specific TCR transgenic CD4 T cells are transferred to mice expressing HEL protein in the pancreas under the control of the rat insulin promoter. Here we show that after adoptive transfer of HEL-specific T cells functional tolerance is maintained despite evidence that the T cells encounter and respond to pancreas-expressed antigen. Even the provision of an additional activation stimulus by peripheral immunization with HEL protein is insufficient to induce the T cells to cause autoimmune tissue injury. However, in the presence of blocking anti-CTLA-4-mAb, immunized adoptive transfer recipients rapidly developed diabetes. These data suggest that the CTLA-4 pathway regulates the pathogenicity of antigen-specific T cells following a peripheral activation stimulus.