Measurement of soluble Fas ligand and specific IgE to D. pteronyssinus
Cord blood soluble Fas ligand levels were measured using an enzyme-linked immunosorbent assay (Human Fas Ligand/TNFSF6 DuoSet ELISA; R & D Systems, Inc., Minneapolis, MN, USA). The D. pteronyssinus -specific immunoglobulin E (IgE) levels were measured by a fluorescent enzyme immunoassay (ImmunoCAP®; detection limit 0.1 kU/L; Phadia, Uppsala, Sweden). Atopy was defined as the value of total IgE > 0.35 kU/L.17