Intragraft donor-specific anti-HLA antibodies in phenotypes of chronic lung allograft dysfunction

Abstract

Introduction: Circulating anti-human leukocyte antigen (HLA) serum donor-specific antibodies (sDSAs) increase the risk of chronic lung allograft dysfunction (CLAD) and mortality. Discrepancies between serological and pathological/clinical findings are common. Therefore, we aimed to assess the presence of tissue-bound graft DSAs (gDSAs) in CLAD explant tissue compared with sDSAs. Methods: Tissue cores, obtained from explant lungs of unused donors (n=10) and patients with bronchiolitis obliterans syndrome (BOS; n=18) and restrictive allograft syndrome (RAS; n=18), were scanned with micro-computed tomography before elution of antibodies. Total IgG levels were measured via ELISA. Anti-HLA class I and II IgG gDSAs were identified using Luminex single antigen beads and compared with DSAs found in serum samples. Results: Overall, mean fluorescence intensity was higher in RAS eluates compared with BOS and controls (p<0.0001). In BOS, two patients were sDSA+/gDSA+ and two patients were sDSA−/gDSA+. In RAS, four patients were sDSA+/gDSA+, one patient was sDSA+/gDSA− and five patients were sDSA−/gDSA+. Serum and graft results combined, DSAs were more prevalent in RAS compared with BOS (56% versus 22%; p=0.04). There was spatial variability in gDSA detection in one BOS patient and three RAS patients, who were all sDSA−. Total graft IgG levels were higher in RAS than BOS (p<0.0001) and in gDSA+ versus gDSA− (p=0.0008), but not in sDSA+ versus sDSA− (p=0.33). In RAS, total IgG levels correlated with fibrosis (r=−0.39; p=0.02). Conclusions: This study underlines the potential of gDSA assessment as complementary information to sDSA findings. The relevance and applications of gDSAs need further investigation.