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Functional capacity of neutrophil granulocytes in deep-sea divers
H B Benestad1, I B Hersleth, H Hardersen
1Institute of Physiology, University of Oslo, Norway.
Abstract:
Neutrophil granulocytes (PMN) are main defenders against invading microbes. We evaluated the adaptive response of PMN from divers exposed for weeks to high total and oxygen pressures. Under these conditions PMN could be primed to give a heightened respiratory burst upon stimulation with the bacterial peptide analogue, formyl-methionyl-leucyl-phenylalanine (FMLP): blood PMN sampled both shortly after operational saturation dives offshore and during an onshore test-dive gave larger responses than control pre- or post-dive PMN from the same subjects and PMN from laboratory personnel. The assays used measured oxygen consumption, intracellular H2O2 availability, and chemiluminescence. The submaximal responses provoked by the non-metabolizable diacylglycerol analogue phorbol myristate acetate (PMA) were less and less often increased. Such enhanced PMN responsiveness may possibly decrease resistance to skin and other infections that are encountered in divers, if PMN thereby failed to localize correctly to inflamed tissues.
Insights
Divers
Area of Science:
- Immunology
- Diving Physiology
- Cellular Biology
Background:
- Neutrophil granulocytes (PMN) are crucial for combating microbial infections.
- Divers experience prolonged exposure to high pressures and oxygen levels.
- Understanding immune system adaptation in divers is vital for their health.
Purpose of the Study:
- To investigate the adaptive immune response of neutrophil granulocytes in divers.
- To assess if prolonged exposure to hyperbaric conditions primes PMN for an enhanced response.
- To evaluate the functional changes in PMN following saturation dives.
Main Methods:
- Blood samples were collected from divers shortly after saturation dives and during onshore test dives.
- Neutrophil granulocyte function was assessed by measuring respiratory burst activity.
- Key assays included oxygen consumption, intracellular hydrogen peroxide (H2O2) availability, and chemiluminescence.
- Responses were compared to pre- and post-dive samples and to control subjects.
Main Results:
- PMN from divers exhibited a heightened respiratory burst response upon stimulation with formyl-methionyl-leucyl-phenylalanine (FMLP).
- This enhanced responsiveness was observed in samples taken shortly after operational dives and during onshore tests.
- Responses to phorbol myristate acetate (PMA) were less consistently increased, suggesting a specific priming mechanism.
- PMN from divers showed significantly larger responses compared to control groups.
Conclusions:
- Prolonged exposure to high pressures and oxygen during saturation dives can prime neutrophil granulocytes.
- This priming results in an enhanced respiratory burst capacity of PMN.
- Such altered PMN function might paradoxically increase susceptibility to infections if immune cells fail to localize properly.