An immunohistochemical study to evaluate the presence of B-cells in chronic lung allograft dysfunction

Introduction: Long term survival after lung transplantation (LTx) is impaired by the development of chronic lung allograft dysfunction (CLAD). CLAD represents 2 phenotypes: restrictive allograft syndrome (RAS) and bronchiolitis obliterans syndrome (BOS), of which the exact pathophysiology remains elusive. The inflammatory role of B-cells has been investigated in diverse chronic pulmonary diseases, however not extensively in LTx. We want to investigate the presence of B-cells in explants lung tissue of CLAD patients. Methods: Sections of BOS (n=14) and RAS (n=16) lungs, collected at re-transplantation, were stained for CD20 and quantified compared to (non-transplant) control lungs (n=21). A subdivision was made into scattered cells and organized cells (follicles). Results were presented as number of cells/mm² area and number of follicles/mm² area. Results: The number of CD20 + B-cells/mm² was increased in RAS (2.62, IQR: 0.84-10.82; p Discussion: Increased B-cell numbers may have an important contribution to the pathogenesis of CLAD, especially in RAS, which warrants further investigation.