Kidney Transplantation in Identical Twins
A young man who had an identical twin donor was recently transplanted. The cause of end-stage disease was IgA nephropathy. The donor had no renal dysfunction or proteinuria. There was no demonstrable HLA mismatch. The panel reactive antibody (PRA) and T- as well as B-cell cross match tests were negative. The post-transplant course was unremarkable. Tacrolimus and MMF-based immunosuppression was maintained until short tandem repeat analysis confirmed genetic identity between donor and recipients.
A 3-month protocol biopsy was performed. It showed no interstitial inflammation, tubulitis, glomerulitis, or peritubular capillaritis. C4d staining was negative. There was no interstitial fibrosis, interstitial fibrosis, or arteriosclerosis. The glomeruli looked unremarkable (Fig 1):
Figure 1. By light microscopy, the glomeruli show normal morphology. No inflammation or tubular injury is seen to suggest a diagnosis of rejection.
However, immunofluorescence and electron microscopic examination showed changes of early IgA nephropathy (Fig 2 and 3):
Figure 2. Immunofluorescence examination should sparse segmentally distributed area of mesangial staining for IgA. No other immunoglobulin or complement components were found.
Figure 3. Electron microscopy showed small areas of immune complex deposition (see arrow) in the paramesangial area.
It has been decided to maintain the patient on 5 mg prednisone. A 12-month protocol biopsy will be performed to determine if the disease progresses. Meanwhile, it has been decided to offer no specific therapy.
It is likely that the biopsy findings represent an early stage of recurrent IgA nephropathy. However, we may also be simply detecting asymptomatic disease in the twin donor. Further follow-up will help differentiate these two possibilities.
This case illustrates how transplants from identical twins can develop immune-mediated diseases that do not fall into the category of rejection. Recurrent glomerulonephritis and death due to a cardiovascular event are the most common causes of graft loss after transplantation between identical twins.
– Post prepared by Parmjeet Randhawa, AJKDBlog Contributor.
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Very interesting and informative case. Something very similar was seen 50 years ago in the original series of recurrent disease in identical twin transplants (Glassock R et al. Medicine (Baltimore), 1968). Perhaps more importantly, it illustrates the value of pre- implantation renal biopsies in renal transplantation (a point made previously by the author of this blog.). A pre-implantation renal biopsy would have very likely detected a “lanthanic” IgA N in the identical twin donor, and differentiated between “Recurrent” and inadvertentntly “Transmitted” IgAN. Treatment is very problematical, but I doubt that 5 mg of Prednisone daily will do very much. The donor will also need careful follow-up in my opinion as there is a high risk that he will develop overt IgAN at some time in the future. Thanks for posting this very interesting case.