What’s in a name? An update on allergenic fungi

Published Online: December 24, 2015

In 1873 British physician Charles Blackley described an attack of bronchial catarrh caused by inhaling spores of the fungus Penicillium glaucum. Since that time, fungal spores have been recognized as a major cause of allergic disease and have been the focus of much research. Fungal classification has undergone numerous changes during this same period; however, the most significant changes in classification have occurred in the last 20 years and these have aided our understanding of fungal allergens.

In a review article in The Journal of Allergy and Clinical Immunology: In Practice, Levetin et al., summarize the current knowledge regarding the taxonomy of allergenic fungi. Today, fungi are recognized as a diverse group of organisms that are classified in their own Kingdom and include organisms such as molds, yeasts, mushrooms, bracket fungi, and puffballs. The authors review the current status of genera in the Kingdom Fungi that are known to produce allergic disease.

Previously, fungal classification was based on the morphology of the sexual state of fungi. Unfortunately, thousands of fungi lack an obvious sexual state and these fungi were formerly placed in an artificial group called the “Deuteromycetes” or “Fungi Imperfecti.”  DNA sequencing over the last 20 years has resolved the classification and eliminated the need for this category, Deuteromycetes, which is now discarded. Today, eight phyla of fungi are recognized, and three of these phyla (Zygomycota, Ascomycota, and Basidiomycota) are associated with the production of important airborne allergens. Advances in classification have also resulted in some name changes of specific fungi; however, because of regulatory constraints many fungal allergen extracts have retained obsolete names.

A major benefit of the reorganization is that specific immunoglobin E (IgE) levels in individuals sensitized to fungi generally reflect the newly resolved phylogenetic relationships of fungi. Recognition of the close relationship between molecular fungal systematics and the IgE sensitization to fungal species provides a systematic way to look at cross-reactivity among fungi.

The Journal of Allergy and Clinical Immunology: In Practice is an official journal of the AAAAI, focusing on practical information for the practicing clinician.

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