SUMMARYThe influence of donor major histocompatibility complex (MHC) class I-or class II-deficiency on the initiation of first-and second-set rejection of mouse heart and liver allografts was examined. C3H (H-2 k ) mice received heterotopic cardiac or orthotopic liver grafts from unmodified B10 (H-2 b ), B6 (H-2 b ), b2m (H-2 b ; class I deficient) or AB 0 (H-2 b ; class II deficient) donors. Organ survival was also investigated in C3H recipients that had been presensitized by a normal B10 skin graft 2-3 weeks before heart or liver transplantation. The absence of cell surface MHC class I or class II resulted in significant prolongation of primary cardiac allograft survival. Three of seven (43%) MHC class I-deficient, and two of five (40%) class II-deficient heart grafts were accepted indefinitely (survival time >100 days). Thus both MHC class I and class II molecules appear to be important for the elicitation of first-set rejection in the heart allograft model. All liver allografts survived >100 days in normal recipients. In C3H recipients that had been presensitized by a B10 skin graft, however, both heart and liver grafts from AB 0 (class II deficient) donors underwent accelerated rejection (median survival time [MST] 3 and 4 days, respectively). In contrast, liver grafts from class I-deficient mice (b2m) were still accepted indefinitely by B10 skin-presensitized C3H recipients, whereas class I-deficient hearts survived significantly longer than those from class II-deficient or normal donors. These data demonstrate that the expression of donor MHC class I, and not class II is crucial in initiating second-set organ allograft rejection. In vitro monitoring revealed that at the time of organ transplant, both splenocytes and serum of the skinpresensitized animals displayed high cytotoxicity against AB 0 (class II-deficient) but not against b2m (class I-deficient) targets.

To our knowledge, the present study is the first to show that human B19V infection is closely associated with thymic hyperplasia and thymic-hyperplasia-associated MG, but is not related to thymoma or thymoma-associated MG. The findings reveal a previously unrecognized aetiopathogenic mechanism of thymic-hyperplasia-associated MG, evoking numerous questions that require further investigation.

Blindness afflicts ~39 million people worldwide. Retinal ganglion cells are unable to regenerate, making this condition irreversible in many cases. Whole-eye transplantation (WET) provides the opportunity to replace diseased retinal ganglion cells, as well as the entire optical system and surrounding facial tissue, if necessary. Recent success in face transplantation demonstrates that this may be a promising treatment for what has been to this time an incurable condition. An animal model for WET must be established to further enhance our knowledge of nerve regeneration, immunosuppression, and technical aspects of surgery. A systematic review of the literature was performed to evaluate studies describing animal models for WET. Only articles in which the eye was completely enucleated and reimplanted were included. Study methods and results were compared. In the majority of published literature, WET can result in recovery of vision in cold-blooded vertebrates. There are a few instances in which mammalian WET models demonstrate survival of the transplanted tissue following neurovascular anastomosis and the ability to maintain brief electroretinogram activity in the new host. In this study we review in cold-blooded vertebrates and mammalian animal models for WET and discuss prospects for future research for translation to human eye transplantation.

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