Ultrastructural localization of the phosphorylcholine-associated antigen in Trichinella spiralis

Two monoclonal antibodies that are specific for phosphorylcholine (PC) were used as probes in immunoelectron microscopy to locate the PC-associated antigen(s) in Trichinella spiralis. This antigen was found to be present abundantly in various internal structures in the muscle larva and the adult worm, but it was virtually absent in the fetal/newborn larva. In the muscle larva, the major pool of PC was found in the inner layer of the body cuticle and in various organelles such as the "rapid-responding" group. No PC-associated antigen, however, was seen on the surface of the cuticle or in the stichocyte granules. In the adult worm and the fetal/newborn larva, the inner layer of cuticle was not stained (or only weakly so) by the antibodies to PC, demonstrating the basic difference in structure between these cuticles and that of the muscle larva.