Glucoamylase is a major allergen of Schizophyllum commune

BACKGROUND: Schizophyllum commune is one of the causative agents of basidiomycosis including disorders such as allergic bronchopulmonary mycosis, allergic fungal sinusitis, and mucoid impaction of bronchi, the incidence of those of which has been increasing. These mycoses are difficult to diagnose because only a limited number of diagnostic tools are currently available. The biggest problem is that no specific antigens of S. commune have been identified to enable serodiagnosis of the disease. OBJECTIVE: In this study, we attempted to identify a major antigen of S. commune to establish a reliable serodiagnostic method. METHODS: We used mass spectrometry to identify an antigen that reacted with the serum of a patient with allergic bronchopulmonary mycosis caused by S. commune. The protein was expressed in Escherichia coli, highly purified, and the patient sera IgG and IgE titres against the protein were determined by enzyme-linked immunosorbent assay. RESULTS: The protein identified as a major antigen of S. commune was named Sch c 1; it was a homolog of glucoamylase. The IgG and IgE titres against Sch c 1 in patient sera were significantly higher than those in healthy volunteer sera (P < 0.01). CONCLUSIONS AND CLINICAL RELEVANCE: Sch c 1 is recognized by the host immune system of patients as an antigen/allergen. The purified glucoamylase Sch c 1 is a promising candidate antigen for the serodiagnosis of S. commune-induced mycosis.