CONICET | Buscador de Institutos y Recursos Humanos

BACKGROUND & AIMS: Intestinal transplantation faces the challenge of grafting a high immunogenic organ, which is certainly one of the major obstacles for intestinal allograft acceptance. The allograft has to guarantee the proper function of the mucosal immune machinery under immunosuppressive conditions. Recently, it has been elucidated that isolated lymphoid follicles(ILFs) are an indispensable part of mucosal immunity to maintain IgA synthesis and consequently to control commensal microflora. No data about these follicular structures in the setting of intestinal transplantation are available so far. Therefore, we addressed the question whether constitution, integrity, and function of allograft ILFs are disturbed by immunosuppressive regimen. METHODS: We compared allograft ILFsfrom terminal ileum of transplanted and non-transplanted patients by flow cytometry, quantitative real time PCR, and immunohistochemistry. Laser dissection microscopy followed by short tandem repeatPCR technology was used for repopulation studies. RESULTS: We refined the technique to identify and isolate ILFs from mucosal tissue. We found that host leukocytes rapidly repopulate allograft ILFs and that the maintenance immunosuppressive regimen, tacrolimus and corticosteroids, does not affecttheir cellular integrity and function. However, allograft ILFs revealed a higher maturation state than in the control samples and IgA positive plasma cells were increased in number in allograft mucosa. CONCLUSIONS: Immunosuppressive regimen has no influence on cell composition and functionality of allograft ILFs. On the contrary, allograft ILFs have a higher level of activity than non-transplanted control samples. Our results open the path for a better understanding of allograft mucosal immunity.

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