Lymphocyte and macrophage activation in bronchoalveolar lavage fluid in nocturnal asthma

Increased nocturnal airway narrowing is thought to occur as a consequence of an intensification of inflammatory processes at night. Lymphocyte and alveolar macrophage (AM) activation are thought to be associated with the clinical expression of asthma, and may be important in the occurrence of nocturnal asthma as well. The expression of CD25 and HLA-DR receptors on lymphocytes from bronchoalveolar lavage (BAL) and peripheral blood (PB) CD4+, as well as of CD14, IgG Fc, and CD11/CD18 leukocyte adhesion receptors on AM in BAL fluid and monocytes in PB, were determined at 16.00 and 04.00 h by flow cytometry. Their relationship with the occurrence of nocturnal asthma was investigated in eight nonatopic controls (Group 1) and 17 atopic asthmatic subjects, prospectively assigned to groups with a mean circadian peak expiratory flow (PEF) variation < 15% (Group 2) and > or = 15% (Group 3). The occurrence of an increased circadian variation in PEF in asthmatic subjects was on the whole not associated with a day-night fluctuation in lymphocyte numbers and subsets in PB or BAL fluid, nor with day-night changes in receptor expression on AM from BAL or monocytes from PB. The only exception was the presence of a greater day-night change in the proportion of HLA-DR-expressing CD4+ lymphocytes in the BAL fluid along with an increasing circadian PEF rhythm in asthmatic subjects (r = 0.68, p = 0.03). A further finding was that a lower number of BAL CD4+ lymphocytes at daytime was significantly related to a higher circadian PEF variation in asthmatic subjects (r = -0.66, p = 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)