Antibody-mediated vascular rejection of kidney allografts: a population-based study.

BACKGROUND: Rejection of allografts has always been the major obstacle to transplantation success. We aimed to improve characterisation of different kidney-allograft rejection phenotypes, identify how each one is associated with anti-HLA antibodies, and investigate their distinct prognoses. METHODS: Patients who underwent ABO-compatible kidney transplantations in Necker Hospital and Saint-Louis Hospital (Paris, France) between Jan 1, 1998, and Dec 31, 2008, were included in our population-based study. We assessed patients who provided biopsy samples for acute allograft rejection, which was defined as the association of deterioration in function and histopathological lesions. The main outcome was kidney allograft loss-ie, return to dialysis. To investigate distinct rejection patterns, we retrospectively assessed rejection episodes with review of graft histology, C4d in allograft biopsies, and donor-specific anti-HLA antibodies. FINDINGS: 2079 patients were included in the main analyses, of whom 302 (15%) had acute biopsy-proven rejection. We identified four distinct patterns of kidney allograft rejection: T cell-mediated vascular rejection (26 patients [9%]), antibody-mediated vascular rejection (64 [21%]), T cell-mediated rejection without vasculitis (139 [46%]), and antibody-mediated rejection without vasculitis (73 [24%]). Risk of graft loss was 9·07 times (95 CI 3·62-19·7) higher in antibody-mediated vascular rejection than in T cell-mediated rejection without vasculitis (p<0·0001), compared with an increase of 2·93 times (1·1-7·9; P=0·0237) in antibody-mediated rejection without vasculitis and no significant rise in T cell-mediated vascular rejection (hazard ratio [HR] 1·5, 95% CI 0·33-7·6; p=0·60). INTERPRETATION: We have identified a type of kidney rejection not presently included in classifications: antibody-mediated vascular rejection. Recognition of this distinct phenotype could lead to the development of new treatment strategies that could salvage many kidney allografts. FUNDING: None.

Complement independent antibody-mediated endarteritis and transplant arteriopathy in mice.

Complement fixation, as evidenced by C4d in the microvasculature, is a widely accepted criterion of antibody-mediated rejection. Complement fixation has been shown to be essential in acute antibody-mediated rejection, but its role in chronic rejection has not been addressed. Previous studies showed that passive transfer of complement fixing monoclonal IgG2a anti-H-2Kk into B6.RAG1-/- KO recipients of B10.BR hearts led to progressive chronic transplant arteriopathy (CTA) over 14-28 days, accompanied by C4d deposition. The present studies were designed to test whether complement was required for these lesions. We report that a noncomplement fixing donor-specific alloantibody (DSA, monoclonal IgG1 anti-H-2Kk) injected into B6.RAG1-/- KO recipients of B10.BR hearts also promotes CTA, without C4d deposition. Furthermore, a passive transfer of DSA (monoclonal IgG2a anti-H-2Kk) initiated endarteritis followed by CTA in B6.RAG1-/- mice genetically deficient in the third component of complement (RAG1-/-C3-/-). These studies indicate that antibody to class I MHC antigens can trigger chronic arterial lesions in vivo without complement participation, in contrast to acute antibody-mediated rejection. This pathway may be relevant to C4d-negative chronic rejection sometimes observed in patients with DSA, and argues that lack of C4d deposition does not exclude antibody-mediated chronic rejection.

Acute and chronic vascular rejection in nonhuman primate kidney transplantation.

A nonhuman primate (NHP) study was designed to evaluate in nonlife-supporting kidney allografts the progression from acute rejection with transplant endarteritis (TXA) to chronic rejection (CR) with sclerosing vasculopathy. Group G1 (n = 6) received high cyclosporine A (CsA) immunosuppression and showed neither TXA nor CR during 90 days post-transplantation. Group G2 (n = 6) received suboptimal CsA immunosuppression and showed severe TXA with graft loss within 46 days (median). Arterial intimal changes included infiltration of macrophages and T lymphocytes (CD3, CD4, CD8) with few myofibroblasts, abundant fibronectin/collagen IV, scant collagens I/III, high rate of cellular proliferation and no C4d accumulation along peritubular capillaries. Group G3 (n = 12) received suboptimal CsA and anti-rejection therapy (rabbit ATG + methylprednisolone + CsA) of TXA. Animals developed CR and lost grafts within 65 days (median). As compared to G2, the arterial intimal changes showed less macrophages and T lymphocytes, an increased number of myofibroblasts, abundant fibronectin/collagen IV and scar collagens I/III, C4d deposition along capillaries in 60% of animals and transplant glomerulopathy in 80% of animals. In conclusion, CR is an immune stimulated process initiated during TXA with the accumulation and proliferation of myofibroblasts, and progressive deposition of collagens in the intima. Our experimental design appears well suited to study events leading to CR.

Endothelial MHC class II antigen expression and endarteritis associated with Marek's disease virus infection in chickens.

Experimental Marek's disease virus (MDV) infection in chickens was used to study the early pathogenesis of virus-induced atherosclerosis. Previous investigations using this model have reported the occurrence of atherosclerotic lesions after approximately 7 months postinfection. In this study, a total of 75 susceptible Cornell P-line chickens were inoculated intraperitoneally with the CU-2 strain of MDV at 3 days of age and subsequently perfused for histologic examination. At 2, 4, 8, 13, and 20 weeks postinoculation, the ascending aorta and the brachiocephalic and coronary arteries were evaluated for early changes. Expression of class II major histocompatibility complex (Ia) antigen by the vascular endothelium was demonstrated by indirect immunodetection as early as 2 weeks after virus inoculation. This change was followed by significant thickening of the intimal layer associated with mononuclear cell infiltration. All the arteries examined from the MDV-infected chickens were affected. Preliminary immunohistochemical staining showed the presence of CD3+ CD4+, and CD8+ cells among the infiltrating cells. The results suggest that an immunopathologic mechanism may be involved in the early pathogenesis of MDV-induced atherosclerosis in chickens.

[Morphologic placenta findings in clinico-serologically verified and suspected rubella infection in the 2d half of pregnancy]. / Morphologische Plazentabefunde bei klinisch-serologisch gesicherter und vermuteter Rötelninfektion in der zweiten Schwangerschaftshälfte.

Rubeola is the congenital infection with the highest rate of embryonal damage. The hematogenous transplacental way of infection also causes morphological changes at the vessels of the placental villi. We examined 38 placentas from up to the 44th week of gestation and the fetus and children belonging to them. We regarded the clinical and serological findings. 6 out of 16 placentas from up to the 18th week of gestation (37.5%) showed endangitis obliterans. Two cases showed changes of the lenses. (Group I). In 10 out of 12 cases from the 19th to the 36th week of gestation (Group II) we found morphological changes in the vessels of the placental villi. The children belonging to them showed nonspecific malformations. From the 37th week of gestation (Group III) half of the placentas was histologically conspicuous. The children did not show malformations specific for rubeola. We refer to the possibilities and limitations of performing light microscopic diagnosis in placenta when there is the suspicion of rubeola infection, intrauterine death of the fetus and postnatal delay of the child's development.