Down-regulated IL-5 receptor expression on peripheral blood eosinophils from budesonide-treated children with asthma.
BACKGROUND
The expression and function of cytokine receptors on peripheral blood eosinophils (PBE) from healthy and asthmatic children are poorly characterized.


METHODS
The PBE count and expression of IL-5 receptor (R) and GM-CSFR positive PBE was analyzed in nonsteroid-treated asthmatic children (n = 13), budesonide-treated asthmatic children (n = 24) and healthy children (n = 16) by flow cytometry. Alterations in intracellular EG2-epitope expression were used to measure the in vitro responsiveness of PBE to recombinant IL-5 and GM-CSF.


RESULTS
The PBE count was increased (P < 0.05) in both asthmatic groups, independent of treatment, as compared to healthy children. The IL-5R expression on PBE, as well as the in vitro responsiveness of PBE to recombinant IL-5, was reduced (P < 0.05), in budesonide-treated asthmatic children compared to nonsteroid-treated asthmatic children and healthy children. The proportion of GM-CSFR positive PBE and in vitro responsiveness of PBE to recombinant GM-CSF were not different between the groups. In vitro treatment with budesonide did not down-regulate the proportion of IL-5R positive PBE.


CONCLUSIONS
Budesonide-treatment of asthmatic children induces a selectively reduced IL-5R expression on PBE, concomitant with a reduced in vitro responsiveness of PBE to IL-5. We suggest that this budesonide-related down-regulation of the IL-5R might be a mechanism by which steroid treatment inhibits the action of IL-5 on eosinophil accumulation and activation in vivo.
Hellman
C
C
Department of Medicine, Division of Clinical Immunology and Allergy, Stockholm, Sweden.
Lönnkvist
K
K
Hedlin
G
G
Halldén
G
G
Lundahl
J
J
D000293:Adolescent; D000893:Anti-Inflammatory Agents / Q000627:therapeutic use*; D001249:Asthma / Q000097:blood* / Q000188:drug therapy*; D001798:Blood Proteins / Q000187:drug effects; D019819:Budesonide / Q000627:therapeutic use*; D002648:Child; D002669:Child Welfare; D004305:Dose-Response Relationship, Drug; D015536:Down-Regulation; D047091:Eosinophil Granule Proteins; D004804:Eosinophils / Q000378:metabolism*; D000939:Epitopes / Q000187:drug effects; D005260:Female; D005541:Forced Expiratory Volume / Q000187:drug effects; D006801:Humans; D015848:Interleukin-5 / Q000097:blood / Q000502:physiology; D008297:Male; D011237:Predictive Value of Tests; D016187:Receptors, Granulocyte-Macrophage Colony-Stimulating Factor / Q000187:drug effects / Q000502:physiology; D018123:Receptors, Interleukin / Q000097:blood* / Q000502:physiology*; D053649:Receptors, Interleukin-5; D012260:Ribonucleases; D012720:Severity of Illness Index; D016896:Treatment Outcome
D000893:Anti-Inflammatory Agents; D001798:Blood Proteins; D047091:Eosinophil Granule Proteins; D000939:Epitopes; D015848:Interleukin-5; D016187:Receptors, Granulocyte-Macrophage Colony-Stimulating Factor; D018123:Receptors, Interleukin; D053649:Receptors, Interleukin-5; D019819:Budesonide; D012260:Ribonucleases