The effects of in vivo antibiotics on neutrophil (PMN) activity in rabbits with peritonitis
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Abstract:
Antibiotics play an important role in helping the host fight infection; however, the direct cellular effect of antibiotics on polymorphonuclear cells remains undefined. Adherence, chemotaxis, phagocytosis, and superoxide anion production are important steps in the cascade of events initiated by the polymorphonucleocyte in bacterial killing. Previous studies have shown inhibition as well as stimulation of neutrophil antibacterial therapy by antibiotics. Peritoneal and blood polymorphonuclear neutrophils (PMN) respond differently to peritonitis and to external agents. The purpose of this study was to investigate the effects of in vivo clindamycin and netilmicin on infected rabbit peritoneal and blood polymorphonuclear adhesiveness, phagocytosis, chemotaxis, and superoxide anion production. Peritoneal and blood PMNs were obtained from rabbits which had undergone appendiceal devascularization 18 hr earlier: antibiotics were administered intramuscularly 1 hr prior to appendectomy and every 8 hr postoperatively for 5 days; these PMNs were compared to infected rabbits which did not receive antibiotics. Clindamycin and netilmicin in vivo cause significant inhibition of phagocytosis, peritoneal adhesiveness, and, when used in combination, blood adhesiveness and peritoneal superoxide anion production. No effects were seen on chemotaxis. Based on this data we conclude that antibiotics, while vitally important in fighting infections, may in and of themselves be agents of immunosuppression at the cellular level.
Insights
Antibiotics can suppress immune cells like polymorphonuclear neutrophils (PMNs), impairing bacterial killing functions such as phagocytosis and adhesiveness. This study reveals potential immunosuppressive effects of antibiotics at the cellular level.
Area of Science:
- Immunology
- Pharmacology
- Microbiology
Background:
- Antibiotics are crucial for fighting infections but their direct cellular effects on host immune cells are not fully understood.
- Polymorphonuclear neutrophils (PMNs) are key in bacterial killing through adherence, chemotaxis, phagocytosis, and superoxide anion production.
- Previous research shows conflicting results regarding antibiotic effects on neutrophil function.
Purpose of the Study:
- To investigate the in vivo effects of clindamycin and netilmicin on rabbit peritoneal and blood PMN functions.
- To assess the impact of these antibiotics on PMN adhesiveness, phagocytosis, chemotaxis, and superoxide anion production during infection.
Main Methods:
- Rabbits with induced peritonitis received intramuscular clindamycin and netilmicin for 5 days.
- Peritoneal and blood PMNs were isolated from treated and untreated infected rabbits.
- Key PMN functions including adherence, phagocytosis, chemotaxis, and superoxide anion production were measured.
Main Results:
- In vivo clindamycin and netilmicin significantly inhibited PMN phagocytosis and peritoneal adherence.
- Combined antibiotic treatment also reduced blood adherence and peritoneal superoxide anion production.
- No significant effects were observed on PMN chemotaxis.
Conclusions:
- Antibiotics, while essential for infection control, may exert immunosuppressive effects at the cellular level by impairing PMN functions.
- These findings highlight a potential trade-off between antibiotic therapy and host immune response.
- Further research is needed to fully elucidate the immunomodulatory roles of antibiotics.