Histamine induces cytoskeletal changes in human eosinophils via the H(4) receptor.
1. Histamine (0.004-2 microm) induced a concentration-dependent shape change of human eosinophils, but not of neutrophils or basophils, detected as an increase in forward scatter (FSC) in the gated autofluorescence/forward scatter (GAFS) assay. 2. The histamine-induced eosinophil shape change was completely abolished by thioperamide (10 microm), an H3/H4 receptor antagonist, but was not inhibited by pyrilamine or cimetidine (10 microm), H1 and H2 receptor antagonists, respectively. The H4 receptor agonists, clobenpropit and clozapine (0.004-2 microm), which are also H3 receptor antagonists, both induced eosinophil shape change, which was inhibited by thioperamide (10 microm). The H3/H4 receptor agonists, imetit, R-alpha-methyl histamine and N-alpha-methyl histamine (0.004-2 microm) also induced eosinophil shape change. 3. Histamine induced actin polymerisation (0.015-10 microm), intracellular calcium mobilisation (10-100 microm) and a significant upregulation of expression of the cell adhesion molecule CD11b (0.004-10 microm) in eosinophils, all of which were inhibited by thioperamide (10-100 microm). In addition, the H4 receptor agonist/H3 receptor antagonist clozapine (20 microm) stimulated a rise in intracellular calcium in eosinophils. 4. Activation of H4 receptors by histamine (1 microm) primed eosinophils for increased chemotactic responses to eotaxin, but histamine (0.1-10 microm) did not directly induce chemotaxis of eosinophils. 5. Pertussis toxin (1 microg ml-1) inhibited shape change and actin polymerisation responses induced by histamine showing that these effects are mediated by coupling to a Galphai/o G-protein. 6. This study demonstrates that human eosinophils express functional H4 receptors and may provide a novel target for allergic disease therapy.
Buckland
Karen F
KF
Biomedical Sciences Division, Faculty of Medicine, Imperial College London, London SW7 2AZ.
Williams
Timothy J
TJ
Conroy
Dolores M
DM
D000199:Actins / Q000378:metabolism; D039481:CD11b Antigen / Q000096:biosynthesis; D002118:Calcium / Q000378:metabolism; D048429:Cell Size / Q000187:drug effects; D054413:Chemokine CCL11; D019742:Chemokines, CC / Q000494:pharmacology; D002633:Chemotaxis / Q000187:drug effects; D003024:Clozapine / Q000494:pharmacology; D003599:Cytoskeleton / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D004804:Eosinophils / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D006632:Histamine / Q000494:pharmacology*; D017442:Histamine Agonists / Q000494:pharmacology; D006633:Histamine Antagonists / Q000494:pharmacology; D006801:Humans; D007093:Imidazoles / Q000494:pharmacology; D037342:Pertussis Toxin / Q000494:pharmacology; D010880:Piperidines / Q000494:pharmacology; D043562:Receptors, G-Protein-Coupled / Q000187:drug effects / Q000502:physiology*; D011968:Receptors, Histamine / Q000187:drug effects / Q000502:physiology*; D000074040:Receptors, Histamine H4; D013890:Thiourea / Q000031:analogs & derivatives* / Q000494:pharmacology; D015854:Up-Regulation
D000199:Actins; C515456:CCL11 protein, human; D039481:CD11b Antigen; D054413:Chemokine CCL11; D019742:Chemokines, CC; C418607:HRH4 protein, human; D017442:Histamine Agonists; D006633:Histamine Antagonists; D007093:Imidazoles; D010880:Piperidines; D043562:Receptors, G-Protein-Coupled; D011968:Receptors, Histamine; D000074040:Receptors, Histamine H4; D006632:Histamine; D037342:Pertussis Toxin; D013890:Thiourea; C052075:thioperamide; D003024:Clozapine; C086108:clobenpropit; D002118:Calcium