Interstitial collagenase secretion and giant cell formation from rabbit alveolar macrophages. Effects of dexamethasone.

Rabbit alveolar macrophages (AM) induced by complete Freund's adjuvant have been used as a model for activated AM. We studied the effects of in vivo and in vitro corticosteroid on collagenase release and spontaneous formation of multinucleated giant cells (MGC) in culture with this system. Dexamethasone 10- through 10(-7) molar concentration in vitro inhibited both collagenase release and spontaneous AM fusion. Daily in vivo administration of dexamethasone to as much as 0.128 mg/kg similarly suppressed these AM functions in culture. These studies show that in vitro and in vivo corticosteroids inhibit collagenase release and MGC formation of rabbit AM in culture in doses comparable to those used therapeutically in humans. This model may be useful in examining the mechanisms of cell fusion and functions of MGC in granulomatous lung disease.