Expression of mucosa-related integrin alpha(E)beta(7) on alveolar T cells in interstitial lung diseases

The expression of alpha(E)beta(7) integrin has been related to the selectiv e retention of lymphocytes in mucosal tissues of gut, urogenital tract and lung. To identify potential disease-associated alpha(E)beta(7) expression p atterns on cells accounting for lymphocytic alveolitis in interstitial lung disease (ILD), alpha(E) expression on CD4(+) and CD8(+) T cell subsets was evaluated by dual-colour flow cytometry in peripheral blood and bronchoalv eolar lavage fluid (BALF) of patients with idiopathic pulmonary fibrosis (I PF; n = 18), hypersensitivity pneumonitis (HP; n = 20) and sarcoidosis (n = 44) in comparison with healthy controls (n = 15). In both healthy individu als and all patient groups the proportion of alpha(E)-bearing T cells in pe ripheral blood was <2%, whereas the vast majority of alveolar CD8(+) T cell s consistently coexpressed alpha(E). Absolute alveolar CD8(+) alpha(E+) cel l numbers/ml were up to 30-fold increased in HP patients. Proportions of al pha(E)-bearing CD4(+) cells in BALF were significantly elevated in IPF (74. 0 +/- 2.7%) and HP (70.0 +/- 2.4%) compared with normals (30.0 +/- 1.8%) (m ean +/- s.e.m.; P < 0.01). In sarcoidosis, the alpha(E) expression on BALF CD4(+) cells displayed subgroup dependency: proportions significantly lower than normal were noted in chest radiographic stage I (14.3 +/- 1.5%), but increased proportions in stages II (50.0 +/- 3.8%) and III (64.0 +/- 4.8%). Correlations between common markers of T cell activation or BALF transform ing growth factor-beta (TGF-beta) bioactivity and alpha(E) expression were not noted. We conclude that the vast majority of alveolar CD8(+) T cells co nsistently express alpha(E)beta(7) and that distinct patterns of alpha(E)be ta(7) expression on alveolar CD4(+) lymphocytes in sarcoidosis are related to the diverse manifestations of the sarcoid inflammatory process in the lu ng.