Presence of IL-4-like molecules in larval excretory-secretory products and crude extracts from Anisakis simplex.

Acute symptoms of anisakidosis are caused by a type I allergic reaction in the gastrointestinal wall with elevated specific immunoglobulin (Ig)E. The purpose of this study was to investigate the presence of interleukin (IL)-4 in the larval antigens of Anisakis simplex. We detected concentrations of IL-4 in pg/ml when larval excretory--secretory products and crude extract from A. simplex were investigated by ELISA. Specific antibodies were obtained by immunization of rabbits with mouse IL-4 and tested in ELISA against A. simplex antigens obtaining higher values of optical density, that were confirmed by western blot analysis. The absorption of these sera with A. simplex antigen resulted in a 70--80% inhibition of antigen binding when retested in ELISA. We demonstrated that A. simplex antigens react with antibodies raised against vertebrate IL-4. The results obtained by us support the hypothesis that A. simplex shares several epitopes with IL-4, important for the Th2 response development in human anisakiasis, where the parasite may modulate the Th1--Th2 dichotomy for its own benefit by mucosal inflammation control in an attempt to avoid the larval expelling.