Tolerance induction by thymic medullary epithelium.
AUTOR(ES)
Hoffmann, M W
RESUMO
To study the role of thymic medullary epithelium in tolerance induction, the third and fourth branchial clefts of embryos from E mu-Kb transgenic mice, which express the major histocompatibility complex class I antigen H-2Kb exclusively on medullary thymic epithelium, were grafted to athymic nude mice. The grafts differentiated into tissue that morphologically resembled normal thymus. These grafts expressed the H-2Kb antigen appropriately and gave rise to a functional T cell repertoire. In vivo tolerance to H-2Kb disparate skin grafts was invariably found in mice expressing H-2Kb in the medulla or in both medulla and cortex of C57BL/6 branchial cleft-grafted controls. In marked contrast, in vitro cytotoxicity assays demonstrated reactivity toward H-2Kb in the presence of interleukin 2, and limiting-dilution analyses showed similar frequencies of cytolytic T cell precursors reactive to H-2Kb and to third-party stimulators. Medullary epithelium can, therefore, induce split tolerance, in which in vivo tolerance is accompanied by strong in vitro responses in the presence of interleukin 2.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=48694Documentos Relacionados
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