Functional assessment of alveolar macrophages: comparison of cells from asthmatics and normal subjects

Alveolar macrophages (AM) were obtained by bronchoalveolar lavage (BAL) from seven healthy nonallergic, nonasthmatic donors, 15 patients with allergic bronchial asthma, and six patients with aspirin-sensitive asthma. AM were purified by adherence over 2 hr and cultured for an additional 24 hr. Functional assessment of viable cells was carried out for zymosan phagocytosis and for prostaglandin (PG) E2-PGF2 alpha and thromboxane (Tx) B2 release by resting and zymosan-stimulated AM. The eosinophil count in BAL fluid from allergic asthmatics was higher than that from control subjects (3.9% +/- 1.6% vs 0.4% +/- 0.3%, p less than 0.05) and still greater in BAL from patients with aspirin-sensitive asthma (21.7% +/- 9.0%, p less than 0.01). After the 24 hr of incubation, the AM viability was inversely correlated to the percentage of eosinophils in BAL fluid (r = -0.54, n = 21, p less than 0.02). Zymosan phagocytosis was significantly lower by viable cells from both allergic asthmatics and aspirin-sensitive patients as compared with cells from normal donors (p less than 0.05). Zymosan phagocytosis induced a twofold to threefold increase in the release of PGE2, PGF2 alpha, and TxB2 from AM of normal subjects (p less than 0.01) but only a onefold to twofold increase from AM of allergic asthmatic patients. The stimulated AM from aspirin-sensitive patients released smaller quantities of each product than AM from normal subjects or allergic asthmatic patients (p less than 0.05). We conclude that the viability and functional activity of AM are impaired in asthmatic patients and that these deficits correlate with the percent eosinophilia in the BAL; it is therefore suggested that they may be due to an interaction between eosinophils and AM in the bronchoalveolar lumen.