Background: Immunoglobulin E–mediated allergies have doubled in prevalence during recent decades in developed countries. This increase has been attributed, in part, to high hygiene standards, which have reduced exposure to microbes. The capacity of microbes to induce type 1 helper T cell (T_H1) responses may imply suppression of T_H2 responses. However, little research has been performed with fungal extracts.

Objectives: To evaluate the T_H1-inducing properties of fungal extracts.

Methods: A total of 24 fungal extracts, including Cetavlon-precipitated polysaccharides from different yeasts, molds, and mushrooms were prepared. The extracts were screened for production of interferon (IFN) γ in human peripheral blood mononuclear cells. The active compounds were further purified by mild acid hydrolysis and by column chromatography and studied in human peripheral blood mononuclear cells.

Results: Expression of IFN-γ was induced by several extracts. The strongest expression of IFN-γ was induced by Candida albicans. The Cetavlon precipitated mannans of fungi induced cytokine responses that were similar or superior to those induced by whole extracts, C albicans being the most potent inducer of IFN-γ. Column chromatography–fractionated mild acid hydrolysis of C albicans mannan was performed. Fractions containing oligosaccharides of 12-16 mannoses induced production of tumor necrosis factor.

Conclusions: Several fungal extracts induce IFN-γ. The most promising preparations were yeast-derived oligosaccharides. Further research should be focused on purification and eventual synthesis of the extracts.

Key words: Candida albicans. Mannan. Mold. Mushroom. T_H1 cell. T_H2 cell. Yeast.