Human umbilical cord blood monocyte-derived eosinophils produce superoxide but not nitric oxide.
OBJECTIVE
To investigate whether in vitro derived eosinophils release nitric oxide (NO), whose role in the pathogenesis of asthma is under intense debate.


METHODS
Human umbilical cord mononuclear cells were isolated from umbilical cord blood cells and cultured in vitro in presence of interleukin-3 and interleukin-5. Superoxide generation was monitored with dihydrorhodamine-123, NO release was estimated by measuring the accumulation of nitrite. Expression of NO synthases proteins was detected by immunoblotting.


RESULTS
Both N-formyl-L-Methionyl-L-Leucyl-L-Phenylalanine, and 1-O-Alkyl-2-acetyl-sn-glyceryl-3-phosphorylcholine induced superoxide release in umbilical cord eosinophils, while no response was observed with lipopolysaccharide, interleukin-4 and/or interferon-gamma. Furthermore, upon activation with different inflammatory stimuli, neither induction of nitric oxide synthesis nor expression of the constitutive and/or inducible nitric oxide synthase were observed in these eosinophils derived in vitro.


CONCLUSIONS
Human umbilical cord derived eosinophils are able to produce superoxide as peripheral blood eosinophils. Whether human peripheral eosinophils are capable of NO synthesis is still the subject of considerable debate, nevertheless, our results suggest that these in vitro derived eosinophils are not capable of nitric oxide synthesis.
Zardini
D M
DM
Centre de Recherche Public, Luxembourg. daniela.zardini@crp-sante.lu
Tschirhart
E J
EJ
D015153:Blotting, Western; D004804:Eosinophils / Q000201:enzymology / Q000378:metabolism*; D005312:Fetal Blood / Q000166:cytology / Q000378:metabolism*; D006801:Humans; D066298:In Vitro Techniques; D009000:Monocytes / Q000378:metabolism*; D009240:N-Formylmethionine Leucyl-Phenylalanine / Q000494:pharmacology; D009569:Nitric Oxide / Q000097:blood*; D019001:Nitric Oxide Synthase / Q000096:biosynthesis; D052247:Nitric Oxide Synthase Type II; D013050:Spectrometry, Fluorescence; D013481:Superoxides / Q000097:blood*
D013481:Superoxides; D009569:Nitric Oxide; D009240:N-Formylmethionine Leucyl-Phenylalanine; C496319:NOS2 protein, human; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II