Characterization of IL-2,IL-4 and IFNr Production by Spleen and Thymus CD4+8-NK1.1- T cells

• Main Authors: chen, Yi-Tiang, 陳宜婷
• Other Authors: Chiang Bor-Luen
• Format: Others
• Language: zh-TW
• Published: 1997
• Online Access: http://ndltd.ncl.edu.tw/handle/23191125494394539501

碩士 === 國立臺灣大學 === 免疫學研究所 === 85 === The thymus plays an important role in the development of T lymphocytes which undergo T cell receptor rearrangement, followed by positive and negative selection, resulting in the shaping of the mature self-MHC restricted and self- antigen tolerant T cell receptor repertoire. Mature CD4+8- or CD4-8+ T cells then migrate to and develop further in peripheral tissues to a stage of functional competence as effector T cells. In this report, we characterized the cytokine (IL-2, IL-4 and IFNg) production potential by conventional CD4+ T cells that have just completed maturation in the thymus and those that have migrated to the periphery. NK1.1+CD4+ T cells belong to a subset of CD4+ T cells characterized by a narrow TCR repertoire usage, in marked contrast to a very diversified TCR repertoire among conventional CD4+ T cells. In addition, NK1.1+CD4+ T cells are MHC class I (CD1)- restricted rather than MHC class II-restricted. Furthermore, they are able to produce large quantities of IL-4 upon primary stimulation in vitro and within minutes upon TCR- crosslinking in vivo, and have therefore been suggested to provide an excellent source of IL-4 and play an important role in immunoregulation. In our studies, after removal of NK1.1+CD4+ T cells, mature thymus CD4+NK1.1- T cells were still able to produce good levels of IL-4 and IFNg but low level of IL-2 upon primary stimulation. Na鴳e CD4+NK1.1- T cells found in the spleen, on the other hand, produce high amounts of IL-2, but very little IL-4 and IFNg, indicating that the likely and rapid transition from IL-4+IFNg+IL-2low to IL-4lowIFNglowIL-2hi producing state upon emigration of thymic T cells into the periphery. Because NK1.1-CD4+ T cells constitute the vast majority of all CD4+ T cells and that they emigrate to peripheral lymphoid tissues on a continuous basis, these mainstream conventional CD4+ T cells may also be a ever present source of IL-4 and IFNg, despite the relative short duration associated with their IL-4 and IFNg producing potential. Since early secretion of IL-4 is critical for the initiation of Th2 type immune response, these conventional recent emigrants may play a role in determining and/or regulation of Th1/Th2 immune response development.