Purpose: House dust mites Dermatophagoides pteronyssinus are the main source of major inhalatory allergens inducing inflammatory response. Mite extract contain both allergenic proteins and lipopolysaccharides (LPS). The main allergenic protein, Der p 2, is a functional homolog of sMD-2, a protein providing blood cell response on LPS. Der p 2 may restore the response to LPS in absence of MD-2, but its interaction with LPS in whole blood is unknown. We studied the effect of Der p 2 on LPS-mediated activation of human whole blood cells.
Methods: Interaction of Der p 2 and LPS was studied on eight healthy donors. The whole blood was incubated with extract of house dust mite Dermatophagoides pteronyssinus (DP-e), recombinant antigenic protein Der p 2 variant 5 (rDep 2), Escherichia coli lipopolysaccharide and their combination. Supernatants were collected for ELISA analysis of protein content. Activation degree was determined by change in concentration of TNF-α, IL-8, IL-1Ra cytokines and sMD-2 protein.
Results: extract of mite Dermatophagoides pteronyssinus (DP-e) possessed weak inherent activity and did not cause significant increase of cytokine production. Simultaneous activation of blood cells by LPS and DP-e led to considerable increase of pro-inflammatory cytokine production. We have shown the intrinsic inducing activity of Der p 2 allergen on sMD-2 protein and TNF-α cytokine expression.
Conclusions: Der p 2 allergen enhances the response of human whole blood cells to external LPS by inducing additional expression of LPS-transporting protein sMD-2. The obtained data show an important role of LPS contamination of allegrens in the progress of allergic inflammatory response.