Increased expression of adhesion molecules (ICAM-1 and LFA-1) on alveolar macrophages from asthmatic patients

In the airways inflammation observed in asthma, activated macrophages are present in increased numbers. Adhesion molecules are required for the cell:cell contacts between leukocytes and endothelial cells or other leukocytes, and they are induced by inflammatory stimuli. We studied the expression of two adhesion molecules (ICAM-1 and LFA-1) on alveolar macrophages recovered by bronchoalveolar lavage from 11 normal subjects and 13 asthmatic patients by using immunocytochemistry. Two specific monoclonal antibodies were used, and the reaction was revealed by the alkaline phosphatase-antialkaline phosphatase (APAAP) method. The percentage of cells expressing ICAM-1 or LFA-1 was significantly increased in asthmatic patients, as compared with normal subjects (P < 0.001 and P < 0.002, respectively; Mann-Whitney U test), and there was a significant correlation with the percentage of cells expressing both markers in asthma (P < 0.03, Spearman rank test). This study highlights the importance of macrophages in the inflammation of asthma and suggests that macrophage interactions with other cells play a role in this inflammation.