Abstract
To clarify the mechanism of human basophil activation via IgG receptors, calcium mobilization in response to IgG antibodies was analyzed in the human basophilic leukemia cell line KU812-F, using flow cytometry. KU812-F cells as well as human basophils selectively expressed the FcγRII subtype of IgG receptor. After stimulation with aggregated IgG, an obvious increase in [Ca2+]i was observed, but the increase was completely inhibited by IV. 3 (anti FcγRIImAb). Moreover, IV. 3 elicited a [Ca2+]i rise only when cross-linked on the cell surface with anti-mouse IgG. No significant histamine release was observed after any IgG stimulation and the biologic function of the FcγRII-induced [Ca2+]i rise remains unclear.
These findings suggest that the cross-linking of FcγRII in KU812-F cells induces signal transduction events and initiates cell activation with the exception of histamine release, and human basophils also may be activated in vivo by IgG antibodies.
