Glucocorticoid modulation of lymphokine-induced giant cell formation

Lymph node lymphocytes from rabbits sensitized with bacillus Calmet Guerin (BCG) secreted into the culture media both macrophage fusion factor (MFF) and migration inhibition factor (MIF) after 24 h of incubation with heat-killed BCG. Cell-free supernatant fluids obtained from these cultures induced simultaneously giant cell formation and migration inhibition of homologous normal alveolar macrophages. The glucocorticoids cortisol (10(-7) M) and dexamethasone (10(-8) M) (DX) consistently inhibited giant cell formation elicited by MFF (P = 0.003) without affecting macrophage viability. By contrast, the same glucocorticoids, in concentrations ranging from 10(-8) to 10(-10) M, induced a considerable increment of giant cell development in macrophage populations exhibiting a low response to MFF. Neither cortisol (10(-4) M) nor DX (10(-4) M) affected the migration inhibition of alveolar macrophages induced by MIF. Present results suggest that the granulomatous response in the rabbit, as reflected by the macrophage fusion assay, may be regulated by glucocorticoids.