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Human granulocyte-macrophage colony-stimulating factor is a neutrophil activator
Abstract:
The polymorphonuclear leukocyte (PMN), or neutrophil, is the major host defence cell protecting the body against invasion by bacteria and fungi. Products of oxidative metabolism mediate PMN microbicidal and tumoricidal activity but the mechanisms by which these pathways become activated are not well understood. We have previously described a human granulocyte-macrophage colony-stimulating factor (GM-CSF) of relative molecular mass (Mr) 22,000 that also inhibits neutrophil motility (NIF-T activity). Because of its direct action on granulocytes, this lymphokine is a candidate for a neutrophil-activating factor. We have studied the effect of GM-CSF/NIF-T on superoxide anion generation in response to the bacterial chemo-attractant N-formylmethionyl-leucylphenylalanine (f-MLP), and report here that PMNs preincubated with either purified natural GM-CSF or biosynthetic (recombinant) GM-CSF showed increased (as much as fourfold) superoxide anion production in response to f-MLP. These results indicate that human GM-CSF is a neutrophil-activating factor.
Insights
Human granulocyte-macrophage colony-stimulating factor (GM-CSF) activates neutrophils, enhancing their ability to fight bacteria and fungi. This immune cell activation involves increased superoxide anion production, crucial for host defense.
Area of Science:
- Immunology
- Cell Biology
- Hematology
Background:
- Polymorphonuclear leukocytes (PMNs), or neutrophils, are key immune cells for combating bacterial and fungal infections.
- Oxidative metabolism products are vital for PMN microbicidal activity, but activation mechanisms remain unclear.
- A previously identified human granulocyte-macrophage colony-stimulating factor (GM-CSF) inhibits neutrophil motility.
Purpose of the Study:
- To investigate the role of human GM-CSF as a neutrophil-activating factor.
- To determine the effect of GM-CSF on superoxide anion generation in neutrophils.
Main Methods:
- Human neutrophils were preincubated with purified natural or recombinant GM-CSF.
- Superoxide anion generation was measured in response to N-formylmethionyl-leucylphenylalanine (f-MLP).
Main Results:
- Neutrophils preincubated with GM-CSF demonstrated significantly increased superoxide anion production (up to fourfold) when stimulated with f-MLP.
- Both natural and biosynthetic GM-CSF exhibited this neutrophil-activating effect.
Conclusions:
- Human GM-CSF acts as a potent neutrophil-activating factor.
- GM-CSF enhances neutrophil oxidative burst capacity, contributing to host defense mechanisms against pathogens.