Spectrum of Immunoregulatory Functions and Properties of Human Alveolar Macrophages

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Abstract
In health, pulmonary alveoli are maintained free of inflammatory responses to inhaled foreign antigens. The specific role of alveolar macrophages (AM) in modulating the local cellular immune response to antigens is controversial. Immunoregulatory function and properties of AM and blood monocytes (MN) were compared. The AM were obtained by bronchoalveolar lavage of healthy volunteers, MN by adherence of peripheral blood mononuclear cells to plastic. These accessory cells were added in increasing ratios to a responder population rendered rigorously accessory cell-dependent by nylon wool adherence and depletion of cells bearing the surface Class II MHC determinant, HLA-DR. At low ratios of mononuclear phagocytes to lymphocytes (< 1.10), MN and AM supported significant and comparable blastogenic responses to tetanus toxoid (3H-thymidine incorporation at a 1:10 ratio was 9,697 ± 2,508 for MN and 8,969 ± 1,454 for AM, mean cpm ± SE, n = 9, p = NS) and other antigens. Interleukin-1 (IL-1) activity in supernatant...