CD28 negative T cells are enriched in granulomatous lesions of the respiratory tract in Wegener's granulomatosis

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Abstract
BACKGROUND Lack of CD28 expression on peripheral blood CD4+ and CD8+ T cells has been reported in patients with Wegener's granulomatosis (WG), suggesting a pathogenetic role of CD28– T cells in WG. METHODS Ten patients with WG and six with sarcoidosis (disease control) were analysed. Fluorescence activated cell sorter (FACS) analysis was used to detect CD28 expression on T cells from peripheral venous blood and from bronchoalveolar lavage (BAL) fluid. T cells in biopsy specimens from granulomatous lesions of the upper respiratory tract were analysed for CD28 expression by double immunofluorescence staining. RESULTS A significantly higher fraction of CD28– T cells was found in the CD4+ and CD8+ T cell compartment in BAL fluid (65.6 (5.4)% and 76.3 (4.1)%, respectively) than in blood (13.4 (6.2)% and 42.9 (6.2)%; pv4.1 (2.5)% and 52.0 (9.4)% in blood). The total number of CD4+/CD28– T cells but not of CD8+/CD28– T cells was also significantly higher in BAL fluid than in blood in patients with WG (pv 6.7 (2.2)%; pv 53.4 (7.3)%; pCONCLUSIONS Our data indicate enrichment of CD28– T cells in BAL fluid and suggest recruitment of CD28– T cells into granulomatous lesions in WG. Further analysis of the phenotype and function of T cell subsets in WG is needed to better understand leucocyte homing in WG and to find new therapeutic targets.