Selective Loss of Donor Specific HLA Antibodies in a Highly Sensitized Patient After Lung Transplantation

Abstract

<h3>Introduction</h3> Lung transplantation in the presence of donor specific antibodies (DSA) is safe with peri-operative desensitization, although persistence of DSA is common. Herein, we present a unique case of a highly sensitized lung transplant recipient with selective loss of DSA post-transplantation. <h3>Case Report</h3> A 65-year-old female with a calculated PRA (cPRA) value of of 17% (class I) and 100% (class II), underwent bilateral lung transplantation for chronic obstructive pulmonary disease. Virtual crossmatch (VCM) was positive, involving DPB1*04:01, DR17, and DR52. The subsequent flow cytometry B-cell crossmatch was strongly positive (median channel shift 296). She received peri-operative desensitization protocol for VCM positive patients, which includes intra-operative and post-operative plasmapheresis, intravenous immune globulin, and anti-thymocyte globulin. Maintenance immunosuppression included cyclosporine (target trough 250-350 umol/L), mycophenolic acid 900mg BID and prednisone 20 mg OD. An increase in DSA reactivity was observed one month after transplant (DPB1*04:01 (MFI=17639), DR17 (MFI=17812), and DR52 (MFI=19414). Repeat HLA testing at 3, 4, and 6 months post-transplant showed sequential reduction of DSAs to below the laboratory cut-off for positivity point despite persistence of non-DSA alloantibodies. The patient continues to maintain good lung function with an FEV1 of 2L (86% of predicted) at 6 months post-transplant. Surveillance transbronchial biopsies at 3 and 6 months were free of cellular rejection. <h3>Summary</h3> Despite initial rebound of pre-formed DSA following peri-operative desensitization, sustained selective clearance of the DSA subsequently occurred in this case, which likely benefited graft function. Similar cases have been reported after combined kidney-liver transplant. Robust laboratory research and prospective studies are required to understand the mechanism of selective DSA elimination in organ transplantation.