ULTRASTRUCTURAL COLOCALIZATION OF PHOSPHORYLCHOLINE AND A PHOSPHORYLCHOLINE-ASSOCIATED EPITOPE IN FIRST-STAGE LARVAE OF TRICHINELLA-SPIRALIS

Although the presence of phosphorylcholine (PC) in Trichinella is well established, the structures of the TSL-4 antigens that bear this epit ope are unknown. A subset of TSL-4 antigens (TSL-8 antigens) has been reported to be absent from the surface of first-stage T. spiralis larv ae. We report experiments with a monoclonal antibody (mAb US2) develop ed in mice with a relative inability to produce antibodies to PC. In i mmunoblotting, mAb US2 and anti-PC mAb (BH8) showed apparently identic al binding patterns. In addition, we used an immunogold double-labelin g technique to study the anatomical distribution of the epitopes recog nized by these mAbs; the results obtained indicate close colocalizatio n of epitopes for BH8 and US2 in tissues of T. spiralis first-stage la rvae. On the basis of these results, we suggest that US2 probably bind s to all T. spiralis TSL-4 antigens, including TSL-8 antigens. We also clarify some conflicting previous reports on the distribution of PC i mmunoreactivity in first-stage larvae of T spiralis.