Ono M, Tochinai S
Division of Biological Sciences, Graduate School of Science, Hokkaido University, Sapporo, Japan.
Transplantation. 1995 Jul 15;60(1):66-70. doi: 10.1097/00007890-199507150-00013.
J-strain (JJ) Xenopus laevis is easily made tolerant to semixenogeneic (X laevis x X borealis: JB) adult skin grafted onto immunologically competent larvae at stages 53-54. If the larvae are thymectomized shortly before skin grafting (late Txd), tolerance will never be induced. This suggests that suppression of the immune response to JB skin is mediated by a population of thymus-derived cells. In an attempt to confirm the presence of these cells, the spleen and tolerated JB skin were tested for their tolerance-inducing activity, by grafting either spleen or skin and a new JB skin piece simultaneously to late Txd JJ larva (secondary host). The results clearly indicated that both spleen and skin possessed the ability to induce tolerance. The injection of 1 x 10(5) splenocytes resulted in induction of tolerance in more than 80% of secondary hosts, and the rate of tolerance induction increased in relation to the injected cell number. Furthermore, tolerance was induced in about 90% of the animals by injecting as few as 100 cells isolated from the tolerated skin. Immunohistochemical observation of grafted skin showed that many host-derived T cells were distributed around the epidermal basal lamina. These results indicate that the cells with suppressive activity are a population of T cells that have differentiated in metamorphosing thymuses and have been released peripherally.
J品系（JJ）非洲爪蟾很容易对在53 - 54期免疫活性幼虫上移植的半异种（非洲爪蟾×北美爪蟾：JB）成年皮肤产生耐受。如果在皮肤移植前不久（晚期胸腺切除）对幼虫进行胸腺切除，就永远不会诱导出耐受。这表明对JB皮肤的免疫反应抑制是由一群胸腺来源的细胞介导的。为了证实这些细胞的存在，通过将脾脏或皮肤与一块新的JB皮肤片同时移植到晚期胸腺切除的JJ幼虫（二级宿主）上，检测脾脏和已产生耐受的JB皮肤的耐受诱导活性。结果清楚地表明脾脏和皮肤都具有诱导耐受的能力。注射1×10⁵个脾细胞可使80%以上的二级宿主诱导出耐受，且耐受诱导率随注射细胞数量增加而升高。此外，通过注射从已产生耐受的皮肤中分离出的仅100个细胞，约90%的动物诱导出了耐受。对接种皮肤的免疫组织化学观察表明，许多宿主来源的T细胞分布在表皮基底层周围。这些结果表明，具有抑制活性的细胞是在变态胸腺中分化并已释放到外周的一群T细胞。
