Immunocytochemical evaluation of Trichinella spiralis larval antigen.

The antigenicity of Trichinella spiralis muscle larvae was studied for the purpose of developing an immunodiagnostic test for trichinosis. Ultrathin sections of fixed larvae were treated with sera from patients with a variety of parasitic infections including trichinosis, anisakiasis, gnathostomiasis, fascioliasis, dirofilariasis, severe trichuriasis, moderate trichuriasis, paragonimiasis, cysticercosis cellulosae hominis and diphyllobothriasis, and then treated with protein A-tagged colloidal gold. The cuticle surface and stichocyte alpha 0- and alpha 1-granules reacted predominantly with sera from trichinosis and severe trichuriasis patients, and negligibly with the others. By contrast, the cuticle inner layer, hypodermis, and hemolymph reacted with all sera examined though there was some variability in the intensity of the staining. These results suggest that the cuticle surface and stichocyte alpha-granules possess a high degree of specificity for antibody-produced in T. spiralis infection, whereas the other larval components exhibit nonspecificity.