Victor M. Arean

Ultrastructural evidence of secretory differentiation in a malignant pleural mesothelioma.

A malignant pleural mesothelioma has shown ultrastructural endocrine type differentiation which may be the morphologic basis for the hypoglycemic syndrome accompanying some of these tumors. The use of electron microscopy in diffuse pleural tumors suspected of being mesotheliomas at the time of biopsy may be of help in distinguishing them from metastatic carcinomas. The ultrastructural examination reveals the biphasic, fibroblastic and epithelial features of mesotheliomas to greater advantage than light‐microscopic observation. This is especially so in the variety of these tumors characterized under the light microscope by a sheetlike growth of spindle and round, seemingly undifferentiated, cells.

Localization of antibody binding sites in the larvae of Ascaris lumbricoides var. suum by means of fluorescent technics

Abstract Antibody binding sites in Ascaris lumbricoides var. suum were determined by direct and indirect fluorescent antibody technics. Binding sites on embryonated eggs, freshly hatched second stage larvae, and larvae isolated from and within the lungs and livers of experimentally infected mice, as well as sections of adult worms were investigated. Specific fluorescent staining was observed in oral, anal, cuticular, and excretory pore precipitates of larvae isolated from tissues and in the cuticle of whole and sectioned larvae. No precipitates were observed on second stage larvae; however, the cuticle stained specifically in both whole and sectioned second stage larvae when incubated in immune fluorescent globulin. Similarly, specific staining of the larval cuticle was noted in sections of embryonated eggs. The “fertilization” membrane of the latter stained nonspecifically. No staining of the cuticle in sections of adult worms was observed; only the periphery of the muscle cells showed specific staining.

In vivo Studies of Ascaris suum Larvae planted in Diffusion Chambers in Immune and Nonimmune Mice.

Second-stage Ascaris suum larvae were placed in Millipore diffusion chambers which excluded host cells. The chambers were planted intraperitoneally in immune and nonimmune mice and removed for study at various time intervals. The larvae survived equally well in the chambers planted in immune and normal mice, but growth of the larvae occurred only in chambers placed in normal mice. Larvae recovered from immune mice resumed growth when transferred to nonimmune mice. Acquired immunity to nematode infection is usually associated with a complex antibody response and an increased inflammatory reaction to tissue invasion and migration by the helminth. The relative immunologic significance of this antibody response and the increased cellular reactivity to helminth infection are difficult to evaluate individually in vivo. The diffusion chamber developed by Algire et al. (1954) has been used in many experimental studies to isolate tissues and cells from the cellular reaction of the host. Huff (1956) proposed that the diffusion chamber offers considerable promise for the study of problems in parasitology, and in 1960 Huff et al. grew exoerythrocytic stages of malaria in diffusion chambers. Recently, Coleman and Fotorny (1962) used a Sellotape diffusion chamber in a study of antibody binding sites on Hymenolepis nana. This investigation was undertaken to study the survival of Ascaris suum larvae in diffusion chambers in both immune and nonimmune mice and to evaluate the influence of humoral factors in immunity to Ascaris infection when cells are not allowed to contact the larvae. MATERIALS AND METHODS Adult female Ascaris suum were obtained from a local abattoir. Eggs were removed and embryonated according to a previously described method (Arean and Crandall, 1962).

Electron microscope observations on the cuticle and submicroscopic binding of antibody in Ascaris suum larvae.

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