Clonidine inhibits IgE-mediated and IgE-independent in vitro histamine release from human basophil leukocytes.
Clonidine, a common antihypertensive agent, was recently shown to inhibit antigen-induced wheal and flare reactions, as well as allergen-evoked bronchoconstriction in allergic patients. In this study we investigated the in vitro anti-allergic properties of clonidine. This alpha 2 adrenoceptor agonist inhibited, in a dose-dependent fashion, basophil histamine secretion elicited by anti-IgE and f-met peptide; it also blocked, though to a lesser extent, the calcium ionophore A23187-induced histamine release. H2 receptor stimulation seems to be responsible for the reduction in histamine release observed, since it can be antagonized by cimetidine, but not by alpha 1, alpha 2 and H1 blockers.
Miadonna
A
A
Department of Internal Medicine, Infectious Diseases and Immunopathology, University of Milan, Italy.
Tedeschi
A
A
Leggieri
E
E
Parravicini
P
P
Lorini
M
M
Zanussi
C
C
D000316:Adrenergic alpha-Agonists / Q000494:pharmacology*; D000328:Adult; D000888:Antibodies, Anti-Idiotypic; D001491:Basophils / Q000187:drug effects*; D000001:Calcimycin / Q000494:pharmacology; D002118:Calcium / Q000494:pharmacology; D002927:Cimetidine / Q000494:pharmacology; D003000:Clonidine / Q000494:pharmacology*; D005260:Female; D006636:Histamine Release / Q000187:drug effects*; D006801:Humans; D007073:Immunoglobulin E / Q000502:physiology; D066298:In Vitro Techniques; D008297:Male; D009240:N-Formylmethionine Leucyl-Phenylalanine / Q000494:pharmacology
D000316:Adrenergic alpha-Agonists; D000888:Antibodies, Anti-Idiotypic; D007073:Immunoglobulin E; D000001:Calcimycin; D009240:N-Formylmethionine Leucyl-Phenylalanine; D002927:Cimetidine; D003000:Clonidine; D002118:Calcium