Reduction in neutrophil cell surface expression of tumor necrosis factor receptors but not Fas after transmigration: implications for the regulation of neutrophil apoptosis.
Klíčová slova
Abstraktní
OBJECTIVE
To test the hypothesis that loss of polymorphonuclear neutrophil tumor necrosis factor alpha (TNF-alpha) receptors during transmigration renders the exudate neutrophil refractory to TNF-alpha-mediated stimulation of apoptosis; and to investigate the surface expression of Fas on both circulating and exudate neutrophils.
METHODS
A prospective cohort study.
METHODS
Surgical laboratory of a tertiary care hospital.
METHODS
Twenty-one healthy human volunteers.
METHODS
All subjects had circulating neutrophils and exudate neutrophils collected by venipuncture and skin window methods, respectively.
METHODS
Circulating and exudate neutrophils were incubated in culture medium (1.0x10(6) neutrophils per milliliter) alone or with TNF-alpha (100 ng/mL). Apoptosis was evaluated by flow cytometry (annexin V-fluorescein isothiocyanate and propidium iodide). Tumor necrosis factor alpha-phycoerythrin and anti-human Fas-fluorescein isothiocyanate were used to evaluate neutrophil TNF-alpha receptors and surface expression of Fas.
RESULTS
Exudate neutrophils had a significant delay in apoptosis rates when compared with circulating neutrophils. The percentage of neutrophils expressing TNF-alpha receptors was significantly diminished after exudation (80%+/-15% vs 33%+/-9%; P<.001), as was the median channel number of TNF-alpha phycoerythrin fluorescence (8.1+/-1.6 vs 5.2+/-0.5; P=.001). However, the expression of Fas was unchanged after transmigration (percentage positive for Fas: 98.7%+/-0.7% vs 92.8%+/-3.4%, P=.89; Fas antibody-fluorescein isothiocyanate median channel fluorescence: 12.2+/-1.1 vs 13.1+/-1.2; P=.80). Exposure of exudate neutrophils to TNF-alpha failed to increase their rate of apoptosis.
CONCLUSIONS
Exudate polymorphonuclear neutrophils are confirmed to have delayed apoptosis. Loss of TNF-alpha receptors during transmigration is necessary for neutrophil survival in the extravascular inflammatory milieu.
