Background: Bronchiolitis obliterans syndrome is the main limitation for long-term survival after lung transplantation. Recent data suggest that some specific B cell populations are associated with long-term graft acceptance and may serve as biomarkers in other organ transplantation. We aimed to monitor B cell profile during early development of bronchiolitis obliterans syndrome after lung transplantation.
Methods: B cell longitudinal profile was analyzed in peripheral blood mononuclear cells from patients with bronchiolitis obliterans syndrome and patients who remained stable regarding pathology development after lung transplantation.
Results: CD24hiCD38hi transitional B cells were only increased in stable patients to reach a peak 24 months after transplantation, whereas remaining unchanged in patients who developed a bronchiolitis obliterans syndrome. We showed that these CD24hiCD38hi transitional B cells specifically secrete IL-10 and express the CD9marker. Thus, patients with a total CD9+ B cell frequency below 6.6% displayed significantly higher incidence of bronchiolitis obliterans syndrome.
Conclusions: These data are the first to associate IL-10-secreting CD24hiCD38hi transitional B cells expressing CD9+ with better allograft outcome in lung transplanted patients. The identification of CD9-expressing B cells as a contributor to a favorable environment essential for the maintenance of long-term stable graft function and as a new predictive biomarker of bronchiolitis obliterans syndrome–free survival provide new strategies for treatment of the pathology and its prediction.