Intravenous (i.v.) Ig (IVIG) also provides an important adjunctive treatment to control airway inflammation, reducing oral steroid requirements in severe bronchial asthma [4–7]. INK 128 purchase The efficacy of IVIG is due largely to IgG, which is a major portion of IVIG. Several roles of IgG in IVIG therapy in autoimmunity have been proposed [8–10], and the functions of IgG in IVIG therapy in allergic diseases are also envisaged to inhibit inflammatory reaction. Although these reports suggest that i.v.-administered

IgG have functions to protect against allergies and asthma, the precise target and mechanisms in allergic airway inflammation have not yet been revealed. In a murine experimental model, intranasal instillation of antigen-specific IgG reportedly learn more reduce eosinophilic inflammation and goblet cell hyperplasia induced by antigen challenge, suggesting that topical IgG reportedly counteracts allergic pulmonary inflammation that is dependent upon Fc and interferon (IFN)-γ[11]. However, clinical use of these therapies in bronchial asthma is currently limited because of the lack of evidence.

Clarifying the role of FcRs leads potentially to the development of a new strategy to manage asthmatic airway disorders. The role of antigen-presenting cells (APCs), including dendritic cells (DCs), in the pathogenesis of asthma has been clarified. When allergens are encountered in the airways, DCs in the airway epithelium capture allergens

and migrate to the draining lymph nodes, where they reside in a mature, antigen-priming mode [12]. There, antigen-specific T cells are induced to differentiate into Th effector cells or regulatory cells by these DCs. Thus, DCs are important in the initiation of T cell differentiation and activation and contribute indirectly to the development of ZD1839 in vitro airway inflammation. Targeting the inhibitory Fc receptor on DCs can potentially inhibit induction of the Th2 cytokine response. We hypothesized that i.v. IgG administration (IVIgG) inhibits allergic inflammation through inhibitory FcRs on immune cells to induce a Th2 response. Among several types of FcRs, FcγRIIb is a unique inhibitory FcR which regulates immune cell function [13]. To verify the inhibitory effects of IVIgG and FcγRIIb in bronchial asthma, we pursued the mechanisms of IVIgG using murine models of allergic airway inflammation induced by ovalbumin (OVA) sensitization and aerosol challenge. As IVIgG, we analyse the effects of both mouse IgG and xenogenic (rabbit) IgG to analyse the functions on FcRs.