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While it is clear that the clinical expression of IgE-mediated diseases depends upon the actions of multiple mediators, histamine, the earliest recognized mediator of allergy, remains a prominent contributor. Histamine released from mast cells binds to specific receptors (H1, H2, H3) to produce its clinical effects. The cardinal features of asthma include smooth muscle spasm, mucosal edema, inflammation and mucus secretion. It has been demonstrated that two of these features, bronchospasm and mucosal edema, can be caused by H1-receptor stimulation, while H2- and possibly H1-activation are probably minor causes of mucus secretion. Histamine interacts directly with the endothelial cells (EC) and induces permeability, a transient expression of P-selectin and the secretion of lipid mediators (e.g. PGI2, PAF and LTB4). Moreover, histamine induces a significant increase of IL-6 and IL-8 secretion by EC. Since IL-8 exerts a chemotactic activity for neutrophils, eosinophils and basophils, and IL-6 is involved in endothelium permeability, the secretion of cytokines may be involved in the late phase reaction. Some antihistamines (i.e., levocabastine, terfenadine, loratadine, azelastine and oxatomide) can reduce ICAM-1 expression. The participation of histamine in the allergic inflammation, including asthma, must be re-examined, since the effects of histamine are more widespread.

We used lumin (4,4'-(3[2(1-ethyl-4-(1-H)quinolidene) ethylidene]) propenylene [bis(1-ethyl quinolinium iodide)]) as a photosensitive cyanin dye and studied its effects on various allergic reactions. We obtained the following results: Lumin slightly inhibited the production of IgE antibody, but showed no effect on the production of IgM and IgG antibodies. Lumin slightly inhibited homologous rat PCA at 48 hr. It also showed some inhibitory activity against histamine (His) release caused by in vitro antigen-antibody reaction. Lumin significantly inhibited the acceleration of the delayed-type hypersensitivity (DTH) reaction by cyclophosphamide (CY). The above results suggest that lumin shows anti-allergic activity through the mediation of immunopharmacological activity.