HLA Class II Positivity by Lysate Crossmatch in Renal Transplant Scenario-Dangerous if Ignored!!!

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The detection of antibodies before transplantation is an important step in assessment of patient immunological risk and exclusion of incompatible donors. Many centers have now implemented donor-specific antibody (DSA) along with complement-dependent cytotoxicity crossmatch (CDC XM) for renal transplant cases. A 34-year-old male with end-stage kidney disease was referred for an ABO-compatible transplant from his mother. The CDC XM done 30 days before transplant was negative. DSA XM was negative for Class I (median fluorescence intensity [MFI] 189) and positive for Class II (MFI 1671). Since CDC and DSA Class I were negative, the nephrologists went ahead with the transplantation. On day 6 posttransplant, serum creatinine showed a rising trend (up to 2.13 mg/dl), and therefore, renal biopsy was done which showed mild acute tubular necrosis with positive C4d staining. DSA XM performed on day 15 posttransplant showed negative Class I (MFI 148) and positive Class II (MFI 9987) confirming antibody-mediated rejection (AMR). The patient was started on steroids, and intravenous immunoglobulin and serial plasma exchanges were performed. Then, DSA Class II levels came down to 1602. DSA levels have been monitored periodically and Class II MFI values have been ranging from 2000 to 4000. The patient is maintained on routine immunosuppression, and a graft is intact with serum creatinine level between 1.7 and 1.8 mg/dl 8 months posttransplant. DSA-isolated Class II positivity in renal transplant recipients correlates strongly with AMR and should be considered clinically significant.