CD57 expression correlates with alveolitis severity in subjects with beryllium-induced disease

BackgroundDespite numerous studies in human beings linking surface phenotype of blood T cells with their functional characteristics, little is known about this relationship on antigen-specific CD4+ T cells residing in a target organ.ObjectiveThe aims of this study were to determine the relationship between CD57 expression, a marker of T-cell senescence, and severity of chronic beryllium disease (CBD) and to determine the phenotypic and functional characteristics that differentiate beryllium-specific CD4+ T cells in lung and blood.MethodsCD57 expression on beryllium-responsive IFN-γ–expressing and IL-2–expressing CD4+ T cells in blood and lung of 17 beryllium-sensitized and 20 CBD subjects was determined.ResultsCD57 expression was significantly higher on bronchoalveolar lavage (BAL) than blood CD4+ T cells in both beryllium-sensitized and CBD subjects. Expression of CD57 on BAL CD4+ T cells was directly correlated with the lymphocytic alveolitis. In blood and BAL, higher CD57 expression was seen on more differentiated CD4+ memory T-cell subsets. Although CD57 expression on blood and BAL cells was associated with a reduced proliferative potential, examination of beryllium-specific CD4+ T cells in blood and lung revealed no difference in CD57 expression on cells that produced IFN-γ only versus IFN-γ and IL-2.ConclusionThese data suggest that CD57 expression on CD4+ T cells is an important phenotypic marker to assess lung inflammation and the functional competence of the CD4+ T-cell compartment in CBD.Clinical implicationsThese findings suggest that CD57 is a marker of lung inflammation and potentially, disease severity.