Résumé : The authors previously documented a quantitative defect in the immunoglobulin G (IgG) response toward bovine betalactoglobulin (BLG), the major cow's milk antigen, and antigen p1 of the house dust mite, Dermatophagoides pteronyssinus (Der p1), in patients with lung cancer. In the Der p1 model, the authors documented at the IgG level an epitope specificity that differed between patients with lung cancer (preferential specificity for cryptic epitopes) and healthy control subjects and patients with mite allergy. The current study investigated whether this varying specificity might be extended to the IgG response toward BLG.