輔助刺激因子與第四介白素在 記憶型CD4+ T 淋巴球生成中所扮演的角色

Abstract

記憶型T淋巴球可抵抗對外來抗原，在免疫系統當中扮演重要的角色。 然而，對於控制記憶型CD4+ T淋巴球產生的詳細機制卻還不甚清楚。 在本研究當中，我們嘗試著去研究輔助刺激因子（costimulatory molecule）是否參與在記憶型CD4+ T淋巴球的生成。 經由cDNA的轉染（transfection）製造出表現在細胞表面帶有CD24、CD40、CD70、CD86、CD153、OX40L、4-1BBL和IcosL的EL4腫瘤細胞株。 另外，為了使這些轉染細胞株（transfectant）可以當作抗原呈現細胞（antigen-presenting cell）以活化CD4+ T淋巴球，因此在每種轉染細胞株的細胞表面上再加以轉染FcgRI，使轉染細胞株可以結合上anti-CD3單株抗體，並將之呈現給CD4+ T淋巴球以刺激之。 在活體外實驗的結果發現，除了CD28:CD86，在其他輔助型因子的刺激之下，CD4+ T淋巴球的活化狀況都不是很好。 因此在利用轉染細胞株EL4活化CD4+ T淋巴球時，我們同時加入anti-CD3和anti-CD28的刺激。 CD4+ T淋巴球在帶有各種不同輔助型刺激因子轉染細胞株EL4的刺激之後，再打入宿主老鼠體內，我們發現細胞表面表現CD40的轉染細胞株，可提供CD40:CD40L的刺激，造成大量長期存活的CD4+ T淋巴球。 另外，我們還發現CD4+ T淋巴球在B淋巴球的刺激之下再外加第四介白素也可以幫助生成長期存活的CD4+ T淋巴球。 至於其他的輔助刺激因子，包括CD28:CD86、CD27:CD70、CD30:CD153、OX40:OX40L、Icos:IcosL和4-1BB:4-1BBL，則對於記憶型CD4 T 淋巴球的生成沒有正向的影響。以上的研究發現對於腫瘤的治療與疫苗的開發皆有所幫助。

Long-lived memory T cells play important roles in the defense against foreign invaders, although the mechanisms involved in memory T cell generation are not fully understood. In this study, I studied the effects costimulatory molecules play on memory CD4+ T cell memory generation. EL4 tumor cell lines that had through transfection been made to stably co-express FcgRI and one or combinations of CD24, CD40, CD70, CD86, CD153, OX40L, 4-1BBL, and IcosL costimulators were used as antigen-presenting cells to activate CD4+ T cells. Such transfectants delivered signal 1 through anti-CD3 mAbs presented by its FcgRI and signal 2 through the given costimulatory molecules it expresses. Except CD28:CD86, all other costimulatory molecules were ineffective at causing CD4+ T cell proliferation. To insure proper activation of CD4 T cells, anti-CD3 and anti-CD28 were both added and were presented via the FcgRI on the various costimulator-expressing EL4 transfectants. Activated CD4+ T cells were adoptively transferred into histocompatible, congenic hosts and their presence was monitored over time. CD4+ T cells activated by anti-CD3/CD28 in the context of CD40:CD154 developed long-term survival potential. In addition, CD4+ T cells activated by anti-CD3/CD28 in the context of B cells + IL-4 also developed long-term survival potential. All other costimulators, CD28:CD86, CD27:CD70, CD30:CD153, OX40:OX40L, Icos:IcosL, and 4-1BB:4-1BBL, did not have positive effects on long-term CD4 memory generation. These results may have implications in tumor therapy and vaccine development.