Comparison of the effect of three adrenal corticosteroids on human granulocyte function against Pseudomonas aeruginosa

Abstract

The effect of hydrocortisone, methylprednisolone, and dexamethasone on the phagocytic and bactericidal capabilities of normal human granulocytes (PMN) was studied under previously described optimal conditions for Pseudomonas aeruginosa, PA 1348A. At hydrocortisone and methylprednisolone concentrations of 1,000 micrograms/ml, delayed phagocytosis was clearly observed, whereas dexamethasone 400 micrograms/ml had no effect on phagocytosis. The bactericidal effect of PMN on PA 1348A was significantly reduced by all three corticosteroids at highest concentrations (p less than 0.05). However, the effect of methylprednisolone was greatest and that of dexamethasone was least evident, 25% and 10% reduction in PMN bactericidal activity, respectively. Following exposure to the highest concentrations of corticosteroids, TEM observations correlated well with the PMN functional assays. While the observations of PMN and bacteria in controls, hydrocortisone, and dexamethasone preparations were similar, evidence for incomplete phagocytosis, lack of vacuole coalescence, minimal disruption of bacterial cell walls, and dividing bacteria in phagosomes were evident in methylprednisolone preparations. These PMN functional and TEM observations suggest that of the three corticosteroids studied, methylprednisolone appears most deleterious to the PMN phagocytic and bactericidal activity.