Induction of basophil desensitization in physiological medium: enhancement after IgE-dependent upregulation of surface IgE binding on basophils.
BACKGROUND
Although the ability of basophils to release mediators, called releasability, may be an important aspect which influences the proinflammatory role of these cells, clinical approaches aiming at the depletion of the releasability have not been established. We examined whether the desensitization procedure in Ca(2+)-containing physiological conditions can make basophils completely unresponsive to IgE-mediated stimulation, and whether basophil desensitization is affected by the surface IgE levels.


METHODS
Human peripheral blood basophils were cultured with low concentrations of anti-IgE antibody or recombinant mite allergen. Following culture, cells were stimulated and their histamine release was measured.


RESULTS
Culturing with mite allergen or anti-IgE antibody below threshold concentrations induced potent desensitization in basophils. The desensitizing effect of anti-IgE was dose- and time-dependent; IgE-dependent releasability was completely suppressed when basophils were incubated with a near-threshold concentration of anti-IgE for > or= 4 h. In the continuous presence of subthreshold doses of anti-IgE, basophils remained desensitized even after 3 days. Basophils which had undergone an increase in surface IgE levels after 24-hour culture with IgE demonstrated enhanced desensitization.


CONCLUSIONS
Near-threshold stimulation in physiological medium can affect basophils, thereby inducing complete and sustained deprivation of releasability without triggering degranulation. Basophil desensitization is regulated by their surface IgE levels. Induction of full desensitization may represent a potentially important therapeutic strategy for IgE-mediated allergic diseases in which basophils play pathogenic roles.
Komiya
Akiko
A
Department of Allergy and Rheumatology, University of Tokyo Graduate School of Medicine, Tokyo, Japan.
Hirai
Koichi
K
Iikura
Motoyasu
M
Nagase
Hiroyuki
H
Yamada
Hirokazu
H
Miyamasu
Misato
M
Ohta
Ken
K
Morita
Yutaka
Y
Ra
Chisei
C
Yamamoto
Kazuhiko
K
Yamaguchi
Masao
M
D000818:Animals; D000888:Antibodies, Anti-Idiotypic / Q000276:immunology; D001249:Asthma / Q000276:immunology; D001491:Basophils / Q000502:physiology*; D006636:Histamine Release; D006801:Humans; D007073:Immunoglobulin E / Q000032:analysis / Q000502:physiology*; D008925:Mites / Q000276:immunology; D017455:Receptors, IgE / Q000032:analysis; D015854:Up-Regulation
D000888:Antibodies, Anti-Idiotypic; D017455:Receptors, IgE; C026408:anti-IgE antibodies; D007073:Immunoglobulin E