Blood CD9+ B cell, a biomarker of bronchiolitis obliterans syndrome after lung transplantation

Bronchiolitis obliterans syndrome is the main limitation for long-term survival after lung transplantation. Some specific B cell populations are associated with long-term graft acceptance. We aimed to monitor the B cell profile during early development of bronchiolitis obliterans syndrome after lung transplantation. The B cell longitudinal profile was analyzed in peripheral blood mononuclear cells from patients with bronchiolitis obliterans syndrome and patients who remained stable over 3 years of follow-up. CD24^hi CD38^hi transitional B cells were increased in stable patients only, and reached a peak 24 months after transplantation, whereas they remained unchanged in patients who developed a bronchiolitis obliterans syndrome. These CD24^hi CD38^hi transitional B cells specifically secrete IL-10 and express CD9. Thus, patients with a total CD9⁺ B cell frequency below 6.6% displayed significantly higher incidence of bronchiolitis obliterans syndrome (AUC = 0.836, PPV = 0.75, NPV = 1). These data are the first to associate IL-10-secreting CD24^hi CD38^hi transitional B cells expressing CD9 with better allograft outcome in lung transplant recipients. CD9-expressing B cells appear 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.

Quality of life assessment in therapeutic trials: rationale for and presentation of a more appropriate instrument

In therapeutic trials, quality of life studies are usually based on a health model which results in a restrictive view. Therefore, it is important to clearly define the concept of the quality of life, since ambiguous concepts can alter the results. The key to this problem is the clear distinction between the two components of the quality of life, ie subjective and objective. This latter component is the only one considered in the current medical approach. The use of the subjective quality of life introduces a number of methodological problems not found when the objective quality of life is assessed, and thus requires a specific model which can be derived from the model of life goals used by sociologists. This model is presented here and illustrated with some results obtained with a new questionnaire, the Subjective Quality of Life Profile (SQLP) questionnaire. We suggest that both subjective and objective quality of life studies should be considered in order to emphasize the humanistic approach to therapeutic indications.