Previous work in animal models indicates that the development of many human autoimmune diseases might be caused

by impairment of the FcR regulatory system [13]. It has been shown that FcγR triggering determination of APC behaviour is an important step in developing a Th2 response and subsequent allergic inflammation. An asthma model using Fc receptor gamma chain (FcRγ)-deficient mice has demonstrated that expression of FcRγ on APCs is important Carfilzomib purchase for the development of allergic airway inflammation and AHR [23]. Deletion of FcRγ results in the deficiency of activating-type FcRs, including FcγRI, FcγRIII and FcεRI, which play important roles as activating Fc receptors, but does not affect the expression or inhibitory function of FcγRIIb. Regnault et al. reported that DCs derived from FcRγ-deficient mice failed to mature normally or promote efficient antigen presentation of peptides from exogenous IgG-complexed antigens [24]. Conversely, a recent report has shown the inhibitory mechanisms of FcγRIIb on CD11c+ APCs in allergic airway inflammation [25]. In this study, FcγRIIb on DCs reportedly controls the cellular maturation state. DCs derived from FcγRIIb-deficient mice showed proliferation Osimertinib of antigen-specific T cells

in vitro and in vivo[26]. These reports indicate that signalling through both activating and inhibitory FcRs regulates the activity of APCs in the immune system in the pathogenesis of asthma. In bronchial asthma, IgE and FcεRI are generally considered to be important and logical therapeutic targets. Omalizmab is available as anti-IgE therapy and binds to free IgE; this results in the reduction of FcεRI on mast cells and basophils filipin [27]. It has been reported that cross-linking of FcεRI with FcγRIIb on mast cells and basophils inhibits the degranulation and release of potent inflammatory mediators [19]. In the alum–OVA model used in this study, development of allergic airway inflammation is not dependent upon the existence of B cells or IgE, but instead on CD4+

T cells [28,29]. These facts suggest that allergic airway inflammation with a Th2 response can be regulated by the FcγRIIb-mediated inhibitory pathway on DCs independently of IgE-FcεRI binding. However, there are a few cases of refractory asthma whose pathogenesis seems to be independent of IgE. To modify the function of lung DCs via FcγRIIb might be one of the additional therapeutic strategies in refractory asthma. For the management of bronchial asthma, it is necessary to approach the pathogenesis with sensitivity to multiple allergens. In one possible candidate for treatment of allergic airway inflammation, Sehra et al. showed that specific allergen–IgG interactions repressed inflammatory responses triggered by bystander allergen, thus suggesting that allergen-specific IgG suppress the immune response induced by other allergens [11].