Stability of Cockroach Allergens Versus Non-allergens

Recent statistical evidence suggests that allergens are more stable and more highly expressed than other proteins from an allergen source. These factors may influence human exposure and, on a smaller scale, stability may affect processing by sentinel dendritic cells skewing the immune response toward allergy. Interestingly, for cockroach allergens purified from frass, the allergen stabilities were not statistically greater than their non-allergen counterparts, likely due to the high mean stability of the latter. To investigate if this was a statistical sampling anomaly, the stability of additional recombinant cockroach allergens was studied. The stability of 6 recombinant cockroach allergens was measured as a function of guanidinium chloride concentration using HNSB and SPROX labeling. Additionally, distant relatives of Bla g 1 (MA proteins) were compared for their thermal stability using temperature dependent circular dichroism as a function of lipid ligand concentration. Bla g 1, 4, 6, and 9 showed elevated stabilities compared to the mean of non-allergen cockroach proteins. However, the differences between allergens and non-allergens was not statistically significant. Additional MA homologues of Bla g 1 demonstrated similar melting temperatures to the latter with no ligand present. However, the stability enhancement due to lipid loading was not present or not as great for other MA proteins compared to Bla g 1 loaded with lipids. Cockroach allergens are highly stable proteins compared to proteins from other allergen sources. However, compared to non-allergens from cockroaches there is not a significant difference, even with data from additional recombinant allergens.