Electron Microscope Observations on the Cuticle and Submicroscopic Binding of Antibody in Ascaris suum Larvae

Abstract

An electron microscope study of the cuticles of secondand third-stage Ascaris suum larvae did not reveal the presence of submicroscopic pores. Ferritin-conjugated immune rabbit globulin was bound to the surface of the cuticle of these larvae. Ferritin-labeled normal rabbit globulin was observed on the cuticles of some secondbut not third-stage larvae. Preliminary electron microscope studies of second-stage larvae isolated from the peritoneal cavity of immune mice after an intraperitoneal injection showed that the peritoneal cells adhered to the cuticles in 4 hr. The cells were mainly macrophages and appeared to be in direct contact with the cuticles of the larvae but no apparent morphologic alteration in the larvae was observed. Fluorescent antibody studies have shown that the cuticles of several nematode species are antigenic (Crandall et al., 1963; Taffs and Voller, 1963; Baratawidjaja et al., 1963). It has been suggested that at least some of the fluorescent antibody binding might be due to antigens within the helminth which pass through submicroscopic pores and adhere to the cuticle (Taffs and Voller, 1963; Jackson, 1963). This investigation was undertaken to determine by electron microscopy whether pores are present in the cuticle of Ascaris suum larvae and to localize the submicroscopic antibody-binding sites on the larvae with ferritinlabeled immune globulin. A preliminary electron microscope study showing the cellular reaction to larvae isolated from the peritoneal cavity of immune mice is