Horton J D, Horton T L, Ritchie P
Department of Biological Sciences, University of Durham, UK.
Dev Comp Immunol. 1993 May-Jun;17(3):249-62. doi: 10.1016/0145-305x(93)90044-q.
Application of adult skin allografts to Xenopus larvae has been a favoured protocol for probing the development of self-tolerance. A more physiologic approach is presented here that examines the immunologic outcome of grafting semi- or fully allogeneic larval skin or spleen to age-matched, larval Xenopus (X. laevis/X. gilli clonal hybrids). Following such grafting at 2 or 4 weeks-of-age, young froglets (4-5-months-old) are generally unable to reject second-set skin transplants, but destroy third-party skin vigorously, the MHC class II-rich spleen proving especially effective at inducing this tolerance. In contrast, following larval grafting of semiallogeneic tissues, mixed leucocyte culture performed at the end of metamorphosis (6 weeks) and again at 6 months reveals splenocyte reactivity toward donor-strain stimulators. Immunohistological findings extend this observation of anti-donor reactivity (suggesting incomplete tolerance) to the graft site. Thus despite excellent health when viewed externally, apparently tolerated second-set skin transplants display localised infiltration (especially into the epidermis) by CD8+ T cells and increased numbers of MHC class I and II-expressing cells by 3 weeks post-grafting. The immunologic implications of these findings are discussed.
将成年皮肤同种异体移植物应用于非洲爪蟾幼体一直是探究自身耐受性发展的一种常用方法。本文提出了一种更符合生理的方法，该方法研究将半同种异体或完全同种异体的幼体皮肤或脾脏移植到年龄匹配的非洲爪蟾（非洲爪蟾/吉利爪蟾克隆杂种）幼体后的免疫结果。在2周龄或4周龄进行此类移植后，幼蛙（4 - 5个月大）通常无法排斥二次皮肤移植，但会强烈破坏第三方皮肤，富含MHC II类分子的脾脏在诱导这种耐受性方面尤其有效。相比之下，在幼体移植半同种异体组织后，在变态末期（6周）和6个月时再次进行混合淋巴细胞培养，结果显示脾细胞对供体菌株刺激物有反应性。免疫组织学研究结果将这种抗供体反应性（提示耐受性不完全）的观察扩展到移植部位。因此，尽管从外部观察健康状况良好，但明显耐受的二次皮肤移植在移植后3周显示出CD8 + T细胞的局部浸润（尤其是侵入表皮）以及表达MHC I类和II类分子的细胞数量增加。本文讨论了这些发现的免疫学意义。
