Natural antibodies to nematode biotinyl-enzymes in human sera

Biotinyl-enzymes are conservative molecules present in helminths, as well a s in other animals, bacteria and plants. They have recently been found to b e antigenic in mice, and a potential source of cross-reactivity among helmi nths. This study investigated the presence in human sera of antibodies reac tive with biotinyl-enzymes from the nematodes Anisakis simplex, Toxocara ca nis and Ascaris suum. Biotinyl-enzymes from all these nematodes were recogn ized by IgG1 antibodies in sera from healthy subjects and from Anisakis-fre e patients infected with other parasites. Interestingly, IgE antibodies rea ctive with Anisakis simplex biotinyl-enzymes were present in about one thir d of the sera from Anisakis-free patients infected with other parasites. Ou r results also demonstrate that the anti-BE IgG1 and IgE antibodies present in the sera of Anisakis-free subjects are cross-reactive among helminths. We conclude that biotinyl-enzymes from nematodes are recognized by natural human antibodies, although Anisakis biotinyl-enzymes do not seem to be the cause of sensitization. Since sera from the Anisakis-free population also p resent these antibodies, as-yet unidentified factors (dietary components, i ntestinal inflammation and/or the presence of parasites) may contribute to the induction of anti-BE antibody background.