Lupus nephritis reoccurs following transplantation in the lupus prone mouse

The incidence and pathomechanism of recurrent lupus nephritis (RLN) after transplantation is not clearly understood. Burning out of the autoimmune process or local immunoregulatory mechanisms in the kidney may be responsible for the low incidence of recurrence. These mechanisms cannot be investigated in human subjects, due to post-transplant immunosuppression. To investigate the pathomechanisms of RLN, male and female kidneys were transplanted from FAS deficient lupus prone (LPR) or control (FAS intact) MRL mice into either LPR or MRL recipients. Urinary protein and blood urea were assessed. Double negative (DN) lymphocyte proliferation was determined by flow cytometry. Two months after transplantation inflammatory infiltration of the glomerular, vascular and interstitial compartments were determined. Renal function as demonstrated by blood urea levels was normal in MRL recipients, but elevated in LPR recipients, independent of the donor strain. Paralleling functional results, inflammatory infiltration was mild or absent in MRL recipients of MRL grafts, and mild to moderate in MRL recipients of LPR grafts, suggesting that kidney removal from the autoimmune (LPR) environment significantly reduced inflammation. Graft infiltration was most severe in LPR recipients: grafts were similarly inflamed independent of the donor. All LPR recipients had significantly less CD4+ Th cells versus MRL mice. Transplantation of LPR grafts into MRL recipients reduced CD4+ Th cell percentage, accompanied by a slight induction of lupus autoantibody production. Our results demonstrate that lupus nephritis is not kidney specific in the LPR model with recurrence after transplantation in the absence of immunosuppression.