Effect of glucocorticosteroids on phagosome-lysosome interaction.

The effects of hydrocortisone on fusion of thorotrast-labeled lysosomes with phagosomes containing killed toxoplasmas was studied. Mouse peritoneal macrophages from glucocorticosteroid-treated animals fromed phagolysosomes just as effectively as macrophages from untreated animals (72% thorotrast-positive vacuoles in hydrocortisone-treated animals; 78% in controls). The electron microscopic appearence of macrophages from treated or untreated animals was similar. This observation complements studies which show no change in intracellular microbicidal activity in macrophages treated with glucocorticosteriods.