Pilarski L M, Howland K L, Deans J P
Department of Immunology, University of Alberta, Edmonton, Canada.
Scand J Immunol. 1994 Apr;39(4):363-72. doi: 10.1111/j.1365-3083.1994.tb03387.x.
Human T-cell development appears to be relatively resistant to cyclosporin A (CsA). Children exposed to CsA in utero as part of kidney transplant maintenance have few abnormalities. The objective of the study described here was to analyse the effects of CsA on the development in vitro of human multinegative (MN) (CD3-4-8-) thymocytes as a model system for thymic progenitor development in vivo. MN thymocytes, prepared by depletion methods, differentiated in vitro to acquire CD3 and undergo transitions in CD45 isoform expression analogous to those postulated to occur in vivo. In this work MN thymocytes were cultured with IL-2 and on thymic epithelial cells (TEC) with or without IL-2, either in the presence or absence of CsA. For many thymocyte preparations, differentiation in the presence of CsA resulted in almost complete inhibition of the acquisition of CD3 and of the low Mr isoform CD45R0. Expression of CD45RA and of total CD45 were reduced but not eliminated and the density of CD29 was unaffected. For others, neither CD3 nor CD45 expression was affected, but selective inhibition of TCR delta expression TCR delta expression occurred. At all doses of CsA (0.1-100 micrograms/ml), MN thymocytes continued to cycle indicating a CsA-resistant generative compartment. Treatment of peripheral blood T cells with CsA had no effect on surface expression of CD3 or CD45 isoforms but did reduce the amount of de novo-synthesized CD45R0 mRNA. Culture of MN thymocytes on TEC rendered them virtually resistant to the negative effects of CsA. CD3 acquisition was unhindered and total CD45 remained high, but the transition from CD45RA to CD45R0 appeared to be delayed. In the absence of TEC, expression of both TCR alpha beta and of TCR delta was inhibited, but on TEC, TCR delta was actually up-regulated in some conditions. The effects of CsA on human thymocyte development appeared to be modulated by the physiological state of the donor and the growth conditions to which the cells were subjected. Conditions which most closely approximated those manifest in vivo rendered thymocytes most resistant to the negative effects of CsA. The amount of CsA required to affect differentiation in vitro was significantly higher than could be attained in vivo suggesting that the immunomodulatory effects of CsA in the maintenance of organ transplants may derive from an as yet uncharacterized mechanism.
人类T细胞发育似乎对环孢素A（CsA）相对具有抗性。作为肾移植维持治疗一部分而在子宫内接触CsA的儿童几乎没有异常情况。此处所述研究的目的是分析CsA对人类多阴性（MN）（CD3 - 4 - 8 -）胸腺细胞体外发育的影响，以此作为体内胸腺祖细胞发育的模型系统。通过去除法制备的MN胸腺细胞在体外分化，获得CD3并经历CD45异构体表达的转变，这与假定在体内发生的情况类似。在这项研究中，MN胸腺细胞在有或无IL - 2的情况下，于胸腺上皮细胞（TEC）上培养，同时有或无CsA。对于许多胸腺细胞制剂而言，在CsA存在的情况下进行分化，几乎完全抑制了CD3的获得以及低分子量异构体CD45R0的表达。CD45RA和总CD45的表达降低但未消除，CD29的密度未受影响。对于其他制剂，CD3和CD45的表达均未受影响，但发生了对TCRδ表达的选择性抑制。在所有剂量的CsA（0.1 - 100微克/毫升）下，MN胸腺细胞继续循环，表明存在一个对CsA有抗性的增殖区室。用CsA处理外周血T细胞对CD3或CD45异构体的表面表达没有影响，但确实减少了新合成的CD45R0 mRNA的量。在TEC上培养MN胸腺细胞使其几乎对CsA的负面影响具有抗性。CD3的获得不受阻碍，总CD45保持高水平，但从CD45RA向CD45R0的转变似乎延迟。在没有TEC的情况下，TCRαβ和TCRδ两者的表达均受到抑制，但在TEC上，在某些条件下TCRδ实际上上调。CsA对人类胸腺细胞发育的影响似乎受到供体的生理状态以及细胞所处生长条件的调节。与体内表现最接近的条件使胸腺细胞对CsA的负面影响最具抗性。在体外影响分化所需的CsA量显著高于体内所能达到的量，这表明CsA在器官移植维持中的免疫调节作用可能源自一种尚未明确的机制。
