Studies of Staphylococcal Enterotoxin B Induced Thymocyte

• Main Authors: Ming-Shiou Jan, 詹明修
• Other Authors: Yee-Shin Lin
• Format: Others
• Language: zh-TW
• Online Access: http://ndltd.ncl.edu.tw/handle/05872467661762324306

碩士 === 國立成功大學 === 微生物及免役學研究所 === 81 === Staphylococcal enterotoxin B (SEB) is a member of enterotoxins secreted by Staphylococcus aureus . SEB stimulates T cells which bear specific Vb segment of T cell receptor (TCR). Recent studies indicate that in addition to stimulation of peripheral T cells, SEB induces programmed cell death (apoptosis) in immature thymocytes. Furthermore, a repeated stimulation of mature T cells results in a state of anergy. Previous studies in our laboratory demonstrated that administration of SEB resulted in the induction of apoptosis especially in immature CD4+CD8+ thymocytes. Glucocorticosteroid has been shown to induce apop- tosis in immature thymocyte both in vivo and in vitro. We first investigate whether thymic hormones might protect thymocytes from SEB-induced apoptosis. Results show that after administration of partially purified thymic hormone to SEB- primed mice, the thymus weight, thymocyte numbers, and immature CD4+CD8+, TCRablow, and Thy1.2high thymocyte subpopulations are partially elevated as compared with the mice treated with SEB alone. Further studies indicate that thymosin b4, but not ProTa, partially reverse SEB- induced thymus atrophy. It has been known that castration causes enlargement of thymus, our data indicate that thymus shrinkage induced by SEB could not be reversed by castration. On the other hand, SEB-induced thymus atrophy is partially reversed by adrenalectomy. In studies of SEB-induced hyporesponsiveness of peripheral T lymphocytes, the results show that in vivo SEB- primed splenocytes exhibit a reduced level of cell proliferation in response to SEB and anti- CD3 mAb, but not to SEA. The SEB-, SEA-, or Con A-stimulated IL-2 production appeared to reduced in splenocytes previously primed with SEB. By third and fourth days following SEB administration, 200 U/ml of IL-2 reverse the cell proliferation to the control level, whereas 50 and 100 U/ml of IL-2 fail to do the same.