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SERUM ANTI-HLA ANTIBODY AND C4D STAINING OF ALLOGRAFT BIOPSIES ARE ADEQUATE TOOLS FOR THE DIAGNOSIS OF HUMORAL REJECTION.
Lorita M. Rebellato, Ph.D. , Kim P. Briley, B.S and Karlene Hewan-Lowe M.D. . Greenville NC, East Carolina University, Brody School of Medicine, 27858, Pathology and Laboratory Medicine .

Humoral rejection is a serious cause of allograft dysfunction. It is difficult to treat and there is no unique detection method. Peritubular capillary deposition of C4d in the allograft biopsy and antidonor HLA antibodies are both markers of humoral rejection. Although each marker is not always complimentary, the use of both markers may be adequate for the detection of humoral rejection.
Method: Renal biopsies and tissue for C4d (Quidel, CA) deposition in the peritubular capillaries by direct immunofluorescence performed on fresh frozen allograft biopsy, was available in 62 patients. Each patient had a serum sample that was tested for the presence of anti donor HLA antibody using an ELISA method (One Lambda). The post transplant period for these patients ranged from 6 to 48 months. Induction immunosuppression consisted of antilymphocyte cytolytic agents or IL2-receptor antibody. Immunosuppression consisted of a calcineurin inhibitor, mycophenolate mofetil and prednisone.
Results: See Table 1.
Conclusion: Rejection in our patient cohort is dominated by cellular rejection. Even when there is a low overall prevalence of humoral rejection, our patients with humoral rejection exhibited anti-HLA antibodies with or without C4d positivity. Serum Anti HLA antibody detection and immunofluorescence staining for C4d are adequate tools for the detection of humoral rejection in the setting of allograft dysfunction.

Table 1.
Total Patients 57
Reason for Allograft Dysfunction
Cellular Rejection, Banff I 3562%
Humoral Rejection, Banff II 712%
With anti-HLA Ab and or C4D+ (5)
Without anti-HLA Ab, C4D- (2)
Other 1526%