Antiphospholipid antibodies and renal transplantation: a risk assessment

Data from 110 transplanted patients show that the presence of antiphospholipid antibodies (aPL) at the time of transplantation is an important risk factor for early renal allograft failure. Sera were tested for IgG, IgM and IgA to CL, PS, PE and PC. Haemodialysis patients had a significantly higher incidence of aPL compared to patients who did not receive haemodialysis (P = 0.0171). aPL-positive ESRD patients on peritoneal dialysis (CAPD) or who had never received haemodialysis were at maximal risk; 100% failure (P = 0.0022). aPL-positive patients receiving haemodialysis were not at such risk. Biopsy findings from the failed kidneys show abundant fibrin deposition in the microvasculature. Serial blood samples from transplanted patients showed aPL titres to decrease immediately after transplant and increase after removal of the failed graft, indicating that aPL specifically target the allografts. To confirm this, we were able to isolate aPL from a failed graft after transplant nephrectomy. Ninety-seven per cent of the aPL-positive patients' historic pre-transplant serum samples demonstrated the presence of the same aPL specificity detected in the final crossmatch sera. The exposure to heparin during haemodialysis suggested to us that heparin reduces the risk of clotting in aPL positive transplant candidates. To lessen the risk of graft loss in aPL positive kidney transplant patients (including CAPD), subcutaneous heparin was administered peri- and post-operatively. To date, none of the heparin-treated aPL-positive transplanted patients suffered an early graft loss. Further, they experienced fewer rejection episodes requiring biopsy and thus are prescribed less steroid therapy than patients not treated with heparin.