The interplay of inflammatory cells, mediators and cytokines during type I allergic reactions in the nose is well described. But even though allergen-specific IgE is known to play a central role for the induction of these events, little is known about nasal B cells and their role in the local allergic reaction. It was the aim of the present study to examine the possibility to isolate and culture B cells from the nose. For this purpose allergic and nonallergic volunteers were challenged by nasal provocation with allergen. Cells were collected sequentially after nasal provocation by nasal lavage, B cells grown in the CD40 system and IgE production assessed by enzyme-linked filter spot assay and radioimmunoassay. IgE-producing B cells were detected after culture of nasal lavage cells in the CD40 system. Elevated levels of IgE were measured in culture supernatants from cells collected during the late-phase allergic reaction. We conclude that B cells can be isolated from the nose and may serve as an interesting source of B cells after in vivo contact with antigen.