Histopathological and Immunohistochemical Study of Acute Renal Allograft Rejection
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Background: Acute cellular rejection remains a major proplem in the management of patients during the early phase after renal transplantation (Erren et al., 1999). Aim: Immunohistochemical study of cellular subpopulations infiltrating rejecting renal allografts in addition to classification by Banff schema 97 with correlation of both to graft survival to determine the prognostic values of these criteria. Materials and methods: Ninety two biopsy specimens from 61 patients who experienced acute graft rejection in Urology and Nephrology Center-Mansoura Faculty of medicine were selected. The biopsy specimens were grouped according to revised Banff 97, in addition to indirect immunoperoxidase staining of interstitial inflammatory infiltrate using six monoclonal antibodies listed in Table (1). Follow up regularly till the end of December 2000 with recording number of rejection episodes and graft survival. Results: The 92 biopsies were classified according to revised Banff schema 97 into group of suspicious for rejection, n=40, type I rejection, n=30, type II rejection, n=18 and type HI, n=4. Statistical analysis revealed significant correlation between grading by Banff schema 97, total number of biopsies, total number of graft episodes, vasculitis, pattern of infiltrate and graft survival. While glomerulitis, tubulitis and severity of infiltrate had no significant relation to graft survival. The immunohistochemical staining revealed predominance of T-lymphocyte infiltrate, mainly T4, followed by cytotoxic cells and macrophage, the natural killer and B-cells participate in renal allograft rejection but without significant value on graft survival. Conclusion: Histopathological and immunohistochemical analysis of interstitial inflammatory infiltrate of renal allograft during acute rejection support the role of cellular immune response, the immunohistochemical analysis has no prognostic value, while the revised Banff schema (97), clinical data such as number of biopsies, number of episodes of rejection and diffuse pattern of infiltrate are associated with poor graft survival. At the same, the degree of vasculitis is the important prognostic indicator for graft outcome.