Cytokine priming of the respiratory burst in human eosinophils is Ca2+ independent and accompanied by induction of tyrosine kinase activity.
We report that pretreatment of human eosinophils with GM-CSF, IL-3, or IL-5 enhanced the respiratory burst induced by opsonized particles. In order to gain more insight into the intracellular mechanism(s) involved in cytokine priming, the role of [Ca2+]i and tyrosine kinases was studied. Optimal priming concentrations of GM-CSF, IL-3, and IL-5 did not induce a rise in [Ca2+]i, and Ca(2+)-depleted eosinophils ([Ca2+]i < 20 nM) were still primed after preincubation with these cytokines. GM-CSF, IL-3, and IL-5 induced phosphorylation of two proteins (102 and 122 kd) on tyrosine residues, as deduced from Western blot analysis with an antiphosphotyrosine monoclonal antibody (4G10). This cytokine-stimulated tyrosine phosphorylation was not inhibited under Ca(2+)-depleted conditions. In conclusion, this study demonstrates that GM-CSF, IL-3, and IL-5 priming of the opsonized particle-induced respiratory burst in human eosinophils is completely Ca2+ independent. Moreover the tyrosine phosphorylation of a 102-kd and a 122-kd protein is Ca2+ independent, suggesting that this event might be involved in cytokine priming.
van der Bruggen
T
T
Department of Pulmonary Diseases, University Hospital Utrecht, The Netherlands.
Kok
P T
PT
Raaijmakers
J A
JA
Verhoeven
A J
AJ
Kessels
R G
RG
Lammers
J W
JW
Koenderman
L
L
D002118:Calcium / Q000097:blood*; D004305:Dose-Response Relationship, Drug; D004790:Enzyme Induction; D004804:Eosinophils / Q000187:drug effects / Q000201:enzymology / Q000502:physiology*; D016178:Granulocyte-Macrophage Colony-Stimulating Factor / Q000494:pharmacology*; D006801:Humans; D066298:In Vitro Techniques; D007377:Interleukin-3 / Q000494:pharmacology*; D015848:Interleukin-5 / Q000494:pharmacology*; D015759:Ionomycin / Q000494:pharmacology; D007700:Kinetics; D008970:Molecular Weight; D010101:Oxygen Consumption / Q000187:drug effects; D010750:Phosphoproteins / Q000097:blood / Q000302:isolation & purification; D010972:Platelet Activating Factor / Q000494:pharmacology; D011505:Protein-Tyrosine Kinases / Q000096:biosynthesis / Q000097:blood*; D011994:Recombinant Proteins / Q000494:pharmacology; D015054:Zymosan / Q000494:pharmacology
D007377:Interleukin-3; D015848:Interleukin-5; D010750:Phosphoproteins; D010972:Platelet Activating Factor; D011994:Recombinant Proteins; D015759:Ionomycin; D016178:Granulocyte-Macrophage Colony-Stimulating Factor; D015054:Zymosan; D011505:Protein-Tyrosine Kinases; D002118:Calcium