These results indicate that, in the

initiation of allergic rhinitis, macrophages in the submandibular lymph nodes are essential not only for IL-4 or immunoglobulin production, but also for class switching of immunoglobulin in lymphocytes. The adaptive immune response is a critical component of host defense against infection and is essential for normal health; however, it is also elicited by antigens (e.g., pollen, food, and drugs) not associated find more with infectious agents, thus causing atopic diseases (1). The prevalence of allergic rhinitis, a typical atopic disease, has recently been increasing worldwide (2). In sensitized subjects, production of specific IgE Abs directed toward an allergen is a prerequisite for the immunologic response leading to allergic rhinitis. Binding of allergen-specific IgE Abs to surface receptors on a wide variety of cells, mainly mast cells and eosinophils (3), and cross-linking of receptor-bound IgE with antigen result in the release of inflammatory mediators that lead to the symptoms of allergic diseases (4). However, several crucial

questions regarding the mechanisms have not yet been fully answered. For example, what kind(s) PF-02341066 cost of immune cells can recognize allergenic molecules as nonself? Are allergens recognized as nonself nonspecifically or specifically by the defense system? Why are IgE Abs rather than IgA, IgM

or IgG Abs, produced towards an allergen? After allergen (e.g., ovalbumin or Schistosoma mansoni egg antigen) sensitization and exposure, serum allergen-specific IgE concentrations are reportedly much higher in BALB/c mice than in C57BL/6 mice (5, 6). We have also found that BALB/c mice produce higher titers of serum IgE Ab than do C57BL/6 mice after treatment with Japanese cedar pollen allergen (Yamamoto et al., unpublished data). Therefore, in the present study, we used BALB/c mice as the experimental animals. Recently, we reported that primary i.n. (or i.p.), but not i.v. (or s.c.), injections of cedar pollen extract without adjuvant induce allergenic activity in the form of an increase in serum IgE, Isoconazole but not IgA, IgG or IgM, Abs. We also found that IgE Abs did not react with the allergen, suggesting the increase was due to nonspecific IgE Abs in the serum (7). In addition, we showed that one or two more s.c. injections of the same allergen without adjuvant into i.n. (or i.p.) or i.v. (or s.c.) allergen-sensitized mice induce allergen-specific IgE Abs production (7). These results indicate that an increase in production of nonspecific IgE Abs without changes in IgA, IgG or IgM concentrations is a prerequisite for production of allergen-specific IgE Abs. Moreover, we found that the lymphocyte-rich fraction of PBMCs from mice sensitized once s.c.