Renal thrombotic microangiopathy associated with anticardiolipin antibodies in hepatitis C-positive renal allograft recipients

Hepatitis C virus (HCV) infection has been associated with de novo or recur rent membranoproliferative glomerulonephritis and acute transplant glomerul opathy in transplanted kidneys. Recently, anticardiolipin antibodies (ACA) have been linked with chronic HCV infection. A few reports have suggested a n association between ACA and renal allograft thrombosis. This study examin es the clinical and pathologic features of HCV-positive renal allograft rec ipients at our institution. From 1990 to 1996, 379 kidney transplants were performed. We identified 18 recipients (4.8%) with HCV-positive serology pr etransplant. Determination of IgG and IgM ACA was performed by enzyme-linke d immunosorbent assay, using pretransplant sera. Among the 18 patients, fiv e patients presented with biopsy-proven de novo renal thrombotic microangio pathy (RTMA), occurring 5 to 120 d (median, 14 d) after transplant. No diff erences in pretransplant characteristics were observed between patients wit h (n = 5) or without (n = 13) RTMA. All five patients had a positive ACA te st (either IgG or IgM titer > 2 SD above normal), compared with only one of 13 patients without RTMA. The mean value for IgG ACA was significantly hig her in the RTMA patients than in patients without RTMA (22.9 +/- 14.1 versu s 6.9 +/- 4.9 IgG phospholipid units, P = 0.02); however, there were no sig nificant differences in IgM ACA titers. Rheumatoid factor and complement C4 levels were normal in pretransplant sera of patients with RTMA. Patients w ith RTMA had their cyclosporine withdrawn (four of five or the dose was dec reased tone of five), and one of five underwent plasmapheresis. Four of fiv e patients died within 5 yr after transplant, compared with no deaths in th e other 13 patients. Finally, as a control group, seven HCV-negative renal allograft recipients who presented with RTMA/hemolytic uremic syndrome duri ng the same time period were found to have normal ACA values (IgG or IgM). RTMA associated with ACA in HCV-positive renal allograft recipients may rep resent a new clinical entity. The occurrence of this syndrome may have dele terious consequences for patient and graft survival.