Mukamoto M, Kodama H, Baba T
Department of Veterinary Science, College of Agriculture, Osaka Prefecture University, Sakai, Japan.
Vet Immunol Immunopathol. 1999 Feb 22;67(3):223-33. doi: 10.1016/s0165-2427(98)00224-4.
We have studied the ability of thymic stromal cells (TSC) and thymocytes to produce cytokines and the involvement of cytokines in intrathymic T cell development. When thymocytes were co-cultured with thymic stromal cells in absence of direct contact and mitogenic stimulation, induction of thymocyte proliferation was observed. Supernatants of cultured stromal cells (TSC-CS) promoted a high proliferative response on CD3- thymocytes but had little effect on CD3+ thymocytes. These results indicate that stromal cells have produced a cytokine which can induce immature thymocyte proliferation. Moreover, stromal cells express the MRNA for stem cell factor (SCF) and c-kit (the receptor for SCF) was detected on CD3- thymocytes but not on CD3+ thymocytes. Since SCF can enhance the proliferation of immature thymocytes in synergy with IL-7 in mammals, there is a possibility that chicken stromal cells may produce a IL-7-like factor. Thymocytes have clearly expressed interferon (IFN)-gamma. In contrast, thymic stromal cells showed no detectable expression of IFN-gamma. CD3+ thymocytes express IFN-gamma MRNA more strongly than CD3 thymocytes, suggesting that IFN-gamma from thymocytes may operate on stromal cells and then may indirectly induce clonal elimination of CD3+ cells on stromal cells. The expression of these cytokines and receptors by thymic stromal cells and thymocyte subpopulations suggests that these cytokines participate in paracrine interactions between these cell populations during thymocyte differentiation.
我们研究了胸腺基质细胞（TSC）和胸腺细胞产生细胞因子的能力以及细胞因子在胸腺内T细胞发育中的作用。当胸腺细胞在无直接接触和丝裂原刺激的情况下与胸腺基质细胞共培养时，可观察到胸腺细胞增殖的诱导。培养的基质细胞上清液（TSC-CS）对CD3-胸腺细胞有高度增殖反应促进作用，但对CD3+胸腺细胞作用很小。这些结果表明基质细胞产生了一种可诱导未成熟胸腺细胞增殖的细胞因子。此外，基质细胞表达干细胞因子（SCF）的mRNA，且在CD3-胸腺细胞上检测到c-kit（SCF的受体），但在CD3+胸腺细胞上未检测到。由于在哺乳动物中SCF可与IL-7协同增强未成熟胸腺细胞的增殖，鸡基质细胞有可能产生一种IL-7样因子。胸腺细胞明显表达干扰素（IFN）-γ。相反，胸腺基质细胞未检测到IFN-γ的表达。CD3+胸腺细胞比CD3-胸腺细胞更强烈地表达IFN-γ mRNA，这表明来自胸腺细胞的IFN-γ可能作用于基质细胞，然后可能间接诱导基质细胞上CD3+细胞的克隆清除。胸腺基质细胞和胸腺细胞亚群对这些细胞因子和受体的表达表明，这些细胞因子在胸腺细胞分化过程中参与了这些细胞群体之间的旁分泌相互作用。
