Are Dust Mite Allergens More Abundant or More Stable Than Other Dermatophagoides Pteronyssinus Proteins?

Abstract

It is frequently reported that allergens are more stable and/or more abundant than other proteins. However, numeric comparisons on a genomic and proteomic scale are lacking. Dermatophagoides pteronyssinus (DP) expression levels were analyzed by RNAseq to assess the relative abundance of all transcripts. Thermodynamic stabilities of proteins in a DP extract were assessed using a mass spectrometry- and chemical denaturation-based strategy. Allergens are among the more highly expressed genes in DP. However allergens are not the most abundant, nor are the allergens a majority of the highly abundant genes. The thermodynamic stabilities of the 919 DP proteins assayed here were on average similar to those previously measured in other eukaryotic species. The 21 DP allergens identified trend toward greater stability than the remaining 898 proteins, but in general the allergens are not exceptionally stable; e.g. Der p 1’s stability is close to the mean. Der p 2 is greater than two standard deviations from the mean, however about 50 other non-allergens were also as stable as Der p 2. When considered together, high abundance and high stability increase the likelihood that a protein is an allergen, however it is not predictive. Allergens are among the more abundant and more stable proteins in DP. However, these features are not unique. In DP extract, commonly used for immunotherapy, the 898 non-allergenic proteins assayed had similar abundance and stability profiles to the 21 known allergens assayed. Abundance and stability do not completely account for the allergenic nature of some proteins.