Humoral and cell-mediated autoimmune reactions to human acidic ribosomal P2 protein in individuals sensitized to Aspergillus fumigatus P2 protein

A panel of cDNAs encoding allergenic proteins was isolated from an Aspergillus fumigatus cDNA library displayed on the surface of filamentous phage. Solid phase-immobilized serum immunoglobulin E (IgE) from A. fumigatus-allergic individuals was used to enrich phage displaying IgE-binding molecules. One of the cDNAs encoded a 11.1-kD protein that was identified as acidic ribosomal phosphoprotein type 2 (P-2 protein). The allergen, formally termed rAsp f 8, shares >62% sequence identity and >84% sequence homology to corresponding eukaryotic P-2 proteins, including human P-2 protein. The sequences encoding human and fungal P-2 protein were subcloned, expressed in Escherichia roll as His(6)-tagged fusion proteins, and purified by Ni2+-chelate affinity chromatography. Both recombinant P-2 proteins were recognized by IgE antibodies from allergic individuals sensitized to the A. fumigatus P-2 protein and elicited strong type 1-specific skin reactions in these individuals. Moreover, human and fungal P-2 proteins induced proliferative responses in peripheral blood mononuclear cells of A. fumigatus-allergic subjects sensitized to the fungal P-2 protein. These data provide strong evidence for in vitro and in vivo humoral and cell-mediated autoreactivity to human P-2 protein in patients suffering from chronic A. fumigatus allergy.