Functional expression of chemokine receptor 2 by normal human eosinophils.
BACKGROUND
Within the granulocytes, the CC chemokines preferentially activate basophils and eosinophils on binding to chemokine receptors (CCRs). In vivo administration of neutralizing anti-monocyte chemoattractant protein 1 (MCP-1) antibodies can block accumulation of eosinophils in the lungs of antigen-challenged animals.


OBJECTIVE
We studied a panel of chemokines for chemotactic activity in normal human eosinophils from healthy donors with a special focus on MCP-1, identified the respective receptor required for the biological response of eosinophils, and investigated mediators used for signal transduction.


METHODS
Cells were enriched by magnetic cell sorting. Receptor expression in eosinophils was shown by RT-PCR and fluorescence-activated cell sorting. The biological response was tested in chemotaxis and calcium mobilization assays.


RESULTS
Eosinophils have detectable mRNA for CCR2, and the receptor protein is expressed on cell surfaces. MCP-1 induces chemotaxis and calcium mobilization in eosinophils. The chemotactic activity of MCP-1 revealed a double-peaked dose-response curve; one of the peaks is abolished by addition of a blocking antibody to CCR2, but it is insensitive to blocking of CCR1 or CCR3. Specific enzyme inhibitors ruled out signaling characteristics of CCR2 in eosinophils.


CONCLUSIONS
Normal human eosinophils express functional CCR2 on cell surfaces.
Dunzendorfer
S
S
Division of General Internal Medicine, Department of Internal Medicine, University of Innsbruck, Austria.
Kaneider
N C
NC
Kaser
A
A
Woell
E
E
Frade
J M
JM
Mellado
M
M
Martínez-Alonso
C
C
Wiedermann
C J
CJ
D020013:Calcium Signaling; D002469:Cell Separation; D018932:Chemokine CCL2 / Q000494:pharmacology*; D002634:Chemotaxis, Leukocyte; D004305:Dose-Response Relationship, Drug; D004804:Eosinophils / Q000166:cytology / Q000276:immunology*; D006801:Humans; D009000:Monocytes / Q000276:immunology; D012333:RNA, Messenger / Q000302:isolation & purification; D054390:Receptors, CCR2; D019707:Receptors, Chemokine / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*
C515334:CCR2 protein, human; D018932:Chemokine CCL2; D012333:RNA, Messenger; D054390:Receptors, CCR2; D019707:Receptors, Chemokine