Calcineurin antagonists differentially affect mediator secretion, p38 mitogen-activated protein kinase and extracellular signal-regulated kinases from immunologically activated human basophils.
BACKGROUND
Basophils participate in allergic diseases by invading affected tissues and secreting histamine, leukotriene (LT)C4, IL-4 and IL-13 following FcepsilonRI cross-linking. A reduction of basophil mediator production is therefore of considerable therapeutical interest. Macrolactam derivatives, which inhibit calcineurin activation, may be candidates for antiallergic therapy as they reduce both symptoms of inflammatory skin disease in animal models and mast cell degranulation.


OBJECTIVE
To investigate the effects of the calcineurin antagonists ascomycin and cyclosporin A on IgE-dependent mediator release from human basophils.


METHODS
Basophils were purified by Ficoll density centrifugation, elutriation and negative selection. Histamine release was measured spectrofluorometrically; LTC4, IL-4 and IL-13 secretions were assayed by enzyme-linked immunosorbent assay (ELISA). Lysed cells were subjected to Western blotting using specific antibodies to phospho-p38 mitogen-activated protein kinase (MAPK) and extracellular signal-regulated kinase (ERK)-1 and -2.


RESULTS
Ascomycin (0.01 nm to 1 micro m) and cyclosporin A (0.1 nm to 10 micro m) strikingly inhibited (maximally 100%) anti-IgE-induced histamine and cytokine release from basophils, and these actions were unaffected by IL-3 priming. Ascomycin, however, was less potent at blocking LTC4 secretion, whereas cyclosporin A was unable to block production of this mediator. In immunoblotting studies, ascomycin and cyclosporin A reduced IgE-dependent p38 MAPK activation but were less potent at reducing ERK phosphorylation in basophils.


CONCLUSIONS
Calcineurin antagonists like ascomycin and cyclosporin A block IgE-dependent basophil degranulation and cytokine synthesis. Calcineurin may target p38 MAPK activation, but seems to have less activity on ERK phosphorylation. This is paralleled by a reduced or even absent effect of calcineurin antagonists on eicosanoid production.
Plath
K E S
KE
Department of Dermatology, Medical University of Lübeck, Ratzeburger Allee 160, D-23538 Lübeck, Germany.
Grabbe
J
J
Gibbs
B F
BF
D001491:Basophils / Q000276:immunology / Q000378:metabolism*; D015153:Blotting, Western; D065095:Calcineurin Inhibitors; D016572:Cyclosporine / Q000494:pharmacology*; D004797:Enzyme-Linked Immunosorbent Assay; D006636:Histamine Release / Q000187:drug effects / Q000502:physiology; D006801:Humans; D007166:Immunosuppressive Agents / Q000494:pharmacology*; D007378:Interleukins / Q000378:metabolism*; D017997:Leukotriene C4 / Q000378:metabolism*; D016559:Tacrolimus / Q000031:analogs & derivatives* / Q000494:pharmacology
D065095:Calcineurin Inhibitors; D007166:Immunosuppressive Agents; D007378:Interleukins; D017997:Leukotriene C4; D016572:Cyclosporine; C058028:immunomycin; D016559:Tacrolimus