Mast cells (MCs) play key roles in
IgE-mediated immunoresponses, including in the protection against
parasitic infections and the onset and/or symptoms of allergic diseases.
IgE-mediated activation induces MCs to release mediators, including
histamine and
leukotriene, as an early response, and to produce
cytokines as a late phase response. Attempts have been made to identify novel
antiallergic compounds from natural materials such as Chinese medicines and
food ingredients. We herein screened approximately 60 compounds and identified
salicylaldehyde, an aromatic
aldehyde isolated from plant
essential oils, as an inhibitor of the
IgE-mediated activation of MCs. A degranulation assay, flow cytometric analyses, and
enzyme-linked
immunosorbent assays revealed that
salicylaldehyde inhibited the
IgE-mediated degranulation and
cytokine expression of bone-marrow-derived MCs (BMMCs). The
salicylaldehyde treatment reduced the surface expression level of FcεRI, the high affinity receptor for
IgE, on BMMCs, and suppressed the
IgE-induced phosphorylation of
tyrosine residues in intercellular
proteins, possibly Lyn, Syk, and Fyn, in BMMCs. We also examined the effects of
salicylaldehyde in vivo using passive
anaphylaxis mouse models and found that
salicylaldehyde administration significantly enhanced the recovery of a reduced body temperature due to systemic
anaphylaxis and markedly suppressed ear swelling, footpad swelling, and vascular permeability in cutaneous
anaphylaxis.