MGL_1304, a major allergen in human sweat for patients with atopic dermatitis and/or cholinergic urticaria, is secreted from Malassezia globose on human skin. The amounts of MGL_1304 and IgE against MGL_1304 are evaluated by the histamine release test using basophils or mast cells sensitized with serum containing IgE against MGL_1304, and enzyme linked sorbent assay (ELISA) using MGL_1304 and anti-MGL_1304 antibodies. Here, we identified a human monoclonal IgE (ABS-IgE) that binds to the high affinity IgE receptor (Fc epsilon RI) and MGL_1304 with high affinity (K-D = 1.99 nM) but does not release histamine from basophils and mast cells. An ELISA using ABS-IgE as a standard IgE revealed that the amount of IgE against MGL_1304 (1000 U/ml) in the standard sera of patients with AD, employed in our previous report, is 32 ng/ml. A sandwich ELISA using ABS-IgE as a detection antibody showed approximately 10 times lower detection limit for MGL_1304 than ELISA in which MGL_1304 is directly bound to an ELISA plate. Moreover, ABS-IgE prevented histamine release from mast cells and basophils by neutralizing MGL_1304 not only in a free form in solution, but also on FceRI expressed on the cell surface without cell activation. ABS-IgE may be used both to quantify the amount of MGL_1304 and anti-MGL_1304 IgE, and possibly for the treatment of diseases caused/aggravated by type I allergy to MGL_1304. (C) 2015 Elsevier Inc. All rights reserved.