Arnall J C, Horton J D
Department of Zoology, University of Durham, U.K.
Immunology. 1987 Oct;62(2):315-9.
Implantation of either major histocompatibility complex (MHC)-disparate thymus to 7-day thymectomized (Tx) Xenopus in late larval life, or allogeneic skin to perimetamorphic controls, routinely induces tolerance towards implant-strain skin grafts applied in adult life. To characterize this allotolerance further, additional in vivo approaches were attempted. Injection of gamma-irradiated (5000 rads) implant-strain splenocytes into frogs bearing tolerant skin grafts revealed (within 3 days) significantly elevated tritiated thymidine uptake by host spleen cells, compared to siblings injected with isogeneic cells. Although this in vivo 'mixed leucocyte reaction' proved to be thymus dependent, the identity of the cells involved awaits clarification. When non-restored Tx Xenopus are injected with live MHC-disparate splenocytes, graft-versus-host (GVH)-induced mortality ensued within 2 weeks. Such GVH disease also occurred (albeit more chronically) when Tx allothymus-implanted animals were given MHC-incompatible splenocytes, but only when these came from the thymus donor strain. Splenocytes from thymus-implanted animals failed to achieve GVH-induced splenomegaly when transferred to appropriate hosts (bearing MHC antigens of the thymus donor strain). Overall, the experiments indicate that alloreactivity against donor cells is impaired but not completely inhibited in Xenopus following perimetamorphic implantation.
在幼体晚期将主要组织相容性复合体（MHC）不相容的胸腺植入7日龄胸腺切除（Tx）的非洲爪蟾，或将同种异体皮肤移植到变态期对照动物身上，通常会诱导对成年期移植的植入品系皮肤移植物产生耐受性。为了进一步表征这种同种耐受性，尝试了其他体内实验方法。将经γ射线照射（5000拉德）的植入品系脾细胞注射到带有耐受性皮肤移植物的青蛙体内，结果显示（3天内），与注射同基因细胞的同胞相比，宿主脾细胞的氚化胸腺嘧啶核苷摄取量显著升高。尽管这种体内“混合淋巴细胞反应”被证明依赖胸腺，但所涉及细胞的身份仍有待阐明。当未恢复的Tx非洲爪蟾注射活的MHC不相容脾细胞时，会在2周内引发移植物抗宿主（GVH）诱导的死亡。当给Tx同种异体胸腺植入动物注射MHC不相容的脾细胞时，也会发生这种GVH疾病（尽管病程更长），但前提是这些脾细胞来自胸腺供体品系。当将胸腺植入动物的脾细胞转移到合适的宿主（带有胸腺供体品系的MHC抗原）时，未能引发GVH诱导的脾肿大。总体而言，实验表明，在变态期植入后，非洲爪蟾对供体细胞的同种反应性受损，但并未完全被抑制。
