Detection of anti-MGL_1304 IgE using the ImmunoCAP system for diagnosis of type I allergy to sweat.

Background: Type I allergy to sweat is involved in the pathogenesis of atopic dermatitis (AD) and cholinergic urticaria (CholU), with MGL_1304 from Malassezia globosa being the major causative antigen. Currently, no standard diagnostic test exists for sweat allergy that uses serum.

Methods: The ImmunoCAP (iCAP) system to measure antigen-specific IgE was developed using recombinant MGL_1304 (rMGL_1304). Using a positive histamine release test (HRT) against the semi-purified sweat antigen (QR) as a criterion for diagnosing sweat allergy, the diagnostic usefulness of anti-MGL_1304 IgE detected through iCAP was analyzed in comparison with conventional anti-Malassezia antigen m227 IgE (anti-m227 IgE).

Results: The iCAP system with rMGL_1304 detected anti-MGL_1304 IgE in serum samples without detection of non-specific reactions. In 93 patients with AD or CholU, of which 58 were HRT-positive, anti-MGL_1304 IgE titers correlated with histamine release levels in HRT against QR better than anti-m227 IgE titers. The cutoff value for sweat allergy diagnosis was 1.55 U_A/mL for anti-m227 IgE (sensitivity: 79.3 %; specificity: 65.7 %) and 0.671 U_A/mL for anti-MGL_1304 IgE (sensitivity: 84.5 %; specificity: 80.0 %). Clinical features of AD and CholU were partially associated with anti-m227 IgE and anti-MGL_1304 IgE titers but not with histamine release in HRT using QR.

Conclusions: Anti-MGL_1304 IgE detection using iCAP is simple and can help diagnosis of sweat allergy with better accuracy than conventional anti-Malassezia antigen IgE.