Anaphylactic shock is characterized by increased capillary permeability and a decline in blood pressure due to excessive production of IgE. Midazolam (MDZ) is reported to have immunomodulatory properties. However, little is known about the effect of MDZ on the production of IgE antibody. We examined whether MDZ can suppress antigenspecific and total IgE production followed by IgE class switch recombination (CSR). MDZ was administered intraperitoneally to mice prior to ovalbumin (OVA) plus native cholera toxin (nCT) immunization. Serum OVA-specific and total IgE responses, and surface IgE-positive B cells were analyzed by ELISA and flow cytometry. Furthermore, expression levels of CSRassociated molecules such as germ-line transcript ε (εGLT), germ-circle tanscript ε (εCT), AID, and Id2 in the spleen were compared. The levels of interferongamma (IFN-γ) and interleukin (IL)-4 mRNA and protein were also examined in the spleen and serum. MDZ significantly suppressed OVA-specific and total IgE levels in plasma and surface IgE-positive B cells in the spleen. Moreover, MDZ-treated mice had significantly reduced levels of εGLT and εCT. Furthermore, although the levels of IFN-γ mRNA and protein were significantly elevated, those of IL-4 were reduced in MDZ-treated mice. Therefore, MDZ may be an important modulator of allergic responses through its ability to downregulate IgE production. (J Oral Sci 56, 77-83, 2014)

Midazolam（MDZ）is reported to have immunomodulatory properties that affect immune cells. However, little is known about the effects of MDZ treatment on Immunoglobulin（Ig） E responses. Therefore, we examined whether MDZ is able to suppress total IgE production, followed by IgE class switch recombination（CSR） , in a mouse model. To assess the effects of MDZ on IgE-CSR, splenic B cells were cultured with LPS, IL-4 and anti-CD40 antibody in the presence or absence of MDZ for 72 h. Total-IgE, interferon-gamma（IFN-γ） responses and surface IgE-positive（sIgE + ）B cells were analyzed by ELISA and flow cytometry. To confirm IgE-CSR, total RNA was isolated from splenic B cells and levels of CSR-associated molecules, such as germ-line transcript ε（εGLT） , germ-circle transcript ε （εCT） , activation-induced cytidine deaminase（AID）and inhibitor of differentiation 2（Id2） were compared. MDZ significantly decreased total IgE production and numbers of sIgE + B cells. Significantly reduced levels of both εGLT-and εCT-specific mRNA were detected in MDZ-treated B cells. In contrast, Id2-specific mRNA transcript, which is a negative regulator for Ig-CSR, was increased on MDZ-treated B cells. Furthermore, MDZ-treated B cell significantly increased IFN-γ production and IFN-γRα expression. These results suggest that MDZ inhibits εGLT and εCT expression, and IgE synthesis via induction of IFN-γ production. MDZ may be useful for preventing IgE-mediated allergic diseases.