The expression of adhesion molecules, including CD11a and CD11b, on the human T lymphocyte surface membrane in...

The beta-2 integrin consists of lymphocyte function-antigen-1 (LFA-1, CD11a/CD18) which binds to the major ligand intracellular adhesion molecules 1 and 2 (ICAM-1 and ICAM-2), Mac-1 (CD11b/CD18, ligand iC3b) and p150,95 (CD11c/CD18, ligand iC3b). These molecules function not only as adhesion molecules but as signal transduction agents. To investigate the expression of an integrin family in asthma, lymphocyte subsets were assessed using bronchoalveolar lavage fluid (BALF) cells obtained from asthma patients. The relationship between the integrins and lymphocyte subpopulations and their activation state in the BALF was analyzed using two-color flow cytometry in 15 subjects with asthma and in 13 control subjects with chronic bronchitis. The absolute number of CD11a+CD4+ lymphocytes was significantly greater in the asthmatics than in the nonsmoking subjects with chronic bronchitis. In the asthmatics, the expression of the CD11a+CD4+ lymphocytes was significantly higher than the expression of CD11a+CD8+ lymphocytes. The CD2+ lymphocytes had a significant positive regression with the CD11a+CD4+ lymphocytes in the asthmatics. These findings indicate that the CD11a+ antigen is mainly located on the CD4+ lymphocytes in asthmatics, and that the subset of CD11a lymphocytes with the CD4+ antigen increases as the absolute number of T lymphocytes increases. Analysis of BALF revealed the representation of integrins for the ongoing bronchial transfer of information, and may provide an approach to obtain evidence about the inflammatory processes on the surface of the bronchioles in asthma.