In connection with our previous work about A. lumbricoides allergen characterization [6,8], in the present work we constructed an A. lumbricoides cDNA library, isolated and expressed a new IgE-binding molecule (Asc l 5), identified its native counterpart in a natural source, analyzed its physicochemical attributes with a focus on aggregation behavior, ligand binding properties, secondary structural elements and bioinformatics analysis, and investigated the IgE-binding frequency and allergenic activity induced by Asc l 5 in humans and in a mouse model of a passive cutaneous anaphylaxis (PCA). This evidence concerns the gene IGHE and posterior cortical atrophy.