Trichinella spiralis: antigenic substances associated with the alimentary tract.

Postembedding immunogold and immunoperoxidase staining methods revealed that substances occupying the lumen of the esophagus and the midgut were antigenic for both Wistar rats and humans. Specificity of the alimentary tract-associated antigen was assessed by reacting these substances with a panel of serum pools from patients with non-Trichinella helminth infections, including anisakiasis, paragonimiasis, gnathostomiasis, fascioliasis, dirofilariasis, and trichuriasis. The substances had no, or negligible, cross-reactivity among the serum pools with the only exception of severe trichuriasis serum. Cytochemical staining revealed that the substances are PAS positive and are stained red by azan, and the midgut-occupying substance was equipped with exposed concanavalin A-binding sites. The present data suggest the alimentary tract-associated antigen can be purified by lectin affinity chromatography and may be used as a fairly specific antigen for immunodiagnostic purposes.