Effect of glucocorticosteroids on the phagocytosis and intracellular killing by peritoneal macrophages
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Abstract:
The effect of hydrocortisone on the phagocytosis and intracellular killing by mouse peritoneal macrophages in vitro was studied by a method making it possible to measure these processes separately. The results showed that in vivo treatment with 15 mg of hydrocortisone acetate did not significantly decrease the phagocytosis of several bacterial species such as Staphylococcus albus, Staphylococcus aureus, Escherichia coli, Salmonella typhimurium, and Pseudomonas aeruginosa. The killing indexes of normal macrophages for the various microorganisms were found to be significantly different. This may indicate that the bactericidal mechanisms are not uniform for these bacteria. The effect of hydrocortisone on the intracellular killing was also variable. For Staphylococcus albus a normal killing index was found. For the other species of bacterial and for Candida albicans some decrease was found, but this was only significant for Salmonella typhimurium. It is concluded that a decrease host resistance due to glucocorticosterioid treatment is not caused by a direct effect of these drugs on the phagocytosis and intracellular killing by mononuclear phagocytes.
Insights
Hydrocortisone acetate treatment did not significantly impair macrophage phagocytosis of bacteria in mice. Intracellular killing effects varied, with no significant decrease in host resistance from glucocorticosteroid therapy.
Area of Science:
- Immunology
- Pharmacology
Background:
- Glucocorticosteroids are known to affect immune function.
- Understanding their impact on macrophage activity is crucial for clinical applications.
Purpose of the Study:
- To investigate the in vitro effects of hydrocortisone on mouse peritoneal macrophage phagocytosis and intracellular killing.
- To determine if glucocorticosteroid treatment directly impairs these key immune functions.
Main Methods:
- Mouse peritoneal macrophages were isolated and treated in vitro.
- Phagocytosis and intracellular killing of various bacterial species (Staphylococcus albus, S. aureus, E. coli, Salmonella typhimurium, Pseudomonas aeruginosa) and Candida albicans were measured separately.
- In vivo hydrocortisone acetate treatment (15 mg) was administered prior to ex vivo analysis.
Main Results:
- In vivo hydrocortisone acetate treatment did not significantly reduce the phagocytosis of tested bacterial species.
- Intracellular killing indexes varied among bacterial species, suggesting diverse bactericidal mechanisms.
- Hydrocortisone's effect on intracellular killing was variable; only Salmonella typhimurium showed a significant decrease.
Conclusions:
- Glucocorticosteroid treatment does not appear to directly impair phagocytosis by mononuclear phagocytes.
- The observed effects on intracellular killing are variable and not uniformly detrimental.
- A decrease in host resistance associated with glucocorticosteroid therapy is unlikely due to a direct negative impact on macrophage phagocytic and killing functions.