Alveolar macrophages from humans and rodents selectively inhibit T-cell proliferation but permit T-cell activation and cytokine secretion.
Alveolar macrophages (AM) are thought to play a key role in the regulation of immune responses within the lung. While it is well established that AM inhibit T-cell proliferation in vitro, it is unclear whether other aspects of the T-cell activation process are also inhibited. The present study demonstrates that AM from rat, mouse and human differ markedly in the potency with which they inhibit mitogen-induced T-cell proliferation, although in humans the degree of inhibition approaches that observed in the animal systems, if antigen (as opposed to mitogen) is employed as the T-cell activating agent. Rodent and human AM also differ in the mechanisms employed to achieve this inhibition; rodent AM appear to utilize reactive nitrogen intermediates, while this does not appear to be the case for human AM. Despite these differences, T cells stimulated in the presence of AM display a similar phenotype in all species examined, i.e. CD3 down-modulation, up-regulation of interleukin-2 receptor (IL-2R) expression and IL-2 production, but inability to respond to IL-2. Thus, AM appear to allow T-cell activation and expression of T-cell effector function, while selectively inhibiting T-cell proliferation.
Upham
J W
JW
Division of Cell Biology, University of Western Australia, Perth.
Strickland
D H
DH
Bilyk
N
N
Robinson
B W
BW
Holt
P G
PG
D000328:Adult; D000594:Amino Acid Oxidoreductases / Q000378:metabolism; D000818:Animals; D017252:CD3 Complex / Q000276:immunology; D002455:Cell Division; D002478:Cells, Cultured; D016207:Cytokines / Q000378:metabolism*; D006801:Humans; D007376:Interleukin-2 / Q000276:immunology; D008213:Lymphocyte Activation; D016676:Macrophages, Alveolar / Q000378:metabolism / Q000502:physiology*; D051379:Mice; D008815:Mice, Inbred Strains; D019001:Nitric Oxide Synthase; D051381:Rats; D011919:Rats, Inbred Strains; D013047:Specific Pathogen-Free Organisms; D013601:T-Lymphocytes / Q000276:immunology*
D017252:CD3 Complex; D016207:Cytokines; D007376:Interleukin-2; D019001:Nitric Oxide Synthase; D000594:Amino Acid Oxidoreductases