Allergens of Curvularia lunata during cultivation in different media

Abstract

Background: Despite enormous efforts toward the standardization of fungal extracts, only a few extracts have been characterized that are relevant for the diagnosis and immunotherapy of allergy-associated disorders. Objective: The goal of this study was to determine the optimum growth condition of Curvularia lunata , an important fungal allergen for quality raw material, and to analyze the C lunata extract for IgE- and IgG–binding proteins. Methods: C lunata was grown in synthetic (Czapeck Dox medium), semisynthetic (Sabouraud’s broth [SB]), and natural media (potato dextrose [PD]) for different periods of time. The extracts were probed for allergenic and antigenic activity, with pooled patient sera and polyclonal antibodies raised against C lunata by means of ELISAs, immunoblots (in vitro), and intradermal tests (in vivo). Results: The growth of C lunata was better in semisynthetic media (ie, SB) compared with other types of media. Dry weight and protein content was maximum in the 7-day culture of SB. ELISA with pooled sera from C lunata –sensitive patients exhibited that cultures grown in SB for 11 to 13 days and PD plus 1.0% agar for 5 days were the most potent. Intradermal tests with 11- to 13-day SB culture extract showed maximum skin reactivity in allergy patients. Immunoblots with patient sera showed 10 to 14 IgE-binding proteins in 5- to 15-day SB cultures. Analysis of 5- to 15-day SB extract with rabbit sera showed 10 to 16 IgG-binding proteins. Conclusions: The extract from 11- to 13-day SB cultures were most biologically potent (intradermal tests) and showed high antigenic and allergenic reactivity (ELISA and immunoblot). The addition of yeast extract did not affect the dry weight and protein content of the C lunata extract. Furthermore, addition of agar in PD medium increases the dry weight and protein content of the fungal mat. Synthetic media was not suitable for mass cultivation of C lunata . (J Allergy Clin Immunol 1999;104:857-62.)