Parathion-induced suppression of humoral immunity in inbred mice.

Numbers of IgM plaque-forming cells (PFC) were reduced by 65% in C57Bl/6 mice given parathion 2 days after immunization with sheep red blood cells (SRBC). The immunosuppressive dose (16 mg/kg, p.o.) caused signs of cholinergic poisoning and 20% mortality. Survivors appeared to have recovered fully from the cholinergic crisis at the time of immunologic assay. However, these animals had reduced tissue cholinesterase (ChE) activities and decreased numbers of nucleated spleen cells. Immunosuppression was apparent on day 4 but not on day 3 or days 5-8 of the primary IgM response. Reduction of serum hemagglutinin titers coincided with reduction of the number of splenic PFC. A lower dose of insecticide (4 mg/kg, p.o.) did not produce signs of poisoning and was not immunosuppressive. The number of 8-day IgG PFC was reduced by 45% when parathion (16 mg/kg, p.o.) was given 6 days after immunization, but not when parathion was given 2 days after immunization. The data suggest that cholinergic stimulation and/or the associated toxic chemical stress may be involved in parathion-induced immunosuppression.

Cadmium-induced suppression of the primary immune response and acute toxicity in mice: differential interaction of zinc.

Four groups of 6-week-old C3H mice were injected sc with either sterile saline, 2.8 mg Cd/kg body weight, 2.8 mg Zn/kg body weight, or 2.8 mg each of Cd and Zn/kg body weight. Forty-eight hours after the initial injection, all mice received a second dose of their respective treatments plus an iv injection of sheep red blood cells. On Days 2, 3, 4, and 5 postimmunization the mice were killed. Spleen cells were used in a hemolytic plaque-forming assay for the quantitation of the primary humoral response. Although the combined administration of zinc and cadmium completely prevented the fatal effects of the cadmium (0 vs 55% mortality), zinc failed to alleviate the cadmium-induced inhibition of the humoral response.

The effects of organophosphate-induced cholinergic stimulation on the antibody response to sheep erythrocytes in inbred mice.

In a previous study, we demonstrated that parathion suppressed both the primary IgM and IgG response to sheep erythrocytes (SRC) in inbred and outbred mice (G. P. Casale, S. D. Cohen, and R. A. DiCapua, 1982, toxicologist 2, 94). Suppression occurred after a dosage which produced cholinergic effects but was absent after a lower dosage which did not produce cholinergic signs. This information suggested that immunosuppression might be mediated indirectly as a result of toxic chemical stress. The present study evaluated the relationship between the anticholinesterase action of parathion, malathion, and dichlorvos (DDVP) and their effects on the primary humoral response to SRC. Male C57Bl/6 mice were given a single dose of parathion (16 mg/kg, po), malathion (720 mg/kg, po), or DDVP (120 mg/kg, po) 2 days after immunization with SRC. Two days later, tissues were removed for cholinesterase (CHE) assay and enumeration of splenic antibody-forming cells (PFC). All three compounds produced moderate to severe cholinergic poisoning. DDVP produced cholinergic signs beginning 1/2 hr after dosing and lasting 1/2 to 1 hr. This profile was associated with a rapid but transient inhibition of brain CHE activity. In contrast, malathion and parathion produced prolonged cholinergic poisoning (4 to 7 hr) and prolonged suppression of brain CHE activity. All three compounds suppressed the primary IgM response. However, when they were given as multiple lower doses, none of the compounds suppressed the primary IgG response. These latter treatments produced no cholinergic signs. The cholinomimetic agent, arecoline (65 mg/kg, ip) produced a short-lived cholinergic crisis but no IgM suppression. Sustained-release arecoline produced prolonged cholinergic poisoning (3 to 5 hr) and reduced the number of IgM PFC to 50% of control. These results demonstrated that organophosphate-induced immunosuppression was associated with severe cholinergic stimulation. The immunosuppression may result from direct action of acetylcholine upon the immune system or it may be secondary to the toxic chemical stress associated with cholinergic poisoning.

Immunochemical characterization of Lymantri dispar NPV hemagglutinin: protein-carbohydrate interaction.

The agglutination of chicken erythrocytes by Lymantria dispar nuclear polyhedrosis virus polyhedrin has been shown to provide specific virus identification. Selected mono- and oligosaccharides, present in blood group substances, were assayed by the Land-steiner hapten inhibition technique for specific inhibition of polyhedrin hemagglutination. N-acetylgalactosamine and N-acetylglucosamine inhibit to the greatest extent; galactosamine, glucosamine and fucose to a lesser extent. The hapten inhibition data suggest that a monosaccharide possessing an equatorial 2-acetamido group interacts most avidly with the polyhedrin-combining site. Bergold demonstrated that the polyhedrin dissociates into six subunits at a pH greater than 10.0. Diafiltration equilibrium and Scatchard analysis indicate that N-acetylgalactosamine binds most avidly to the polyhedrin (Kd = 1.7 X 10(-6)) which contains six available sites, suggesting that one hemagglutination site resides on each subunit. Since virions derived in vivo and polyhedrin are serologically cross-reactive, this protein-carbohydrate interaction may play a role in host infectivity by providing a receptor site for virus attachment to target cells.

Morphogenesis of marek's disease virus in feather follicle epithelium.

Three evaluative systems, immunodiffusion, fluorescent antibody (FA), and electron microscopy (EM), were used to follow the morphogenesis of Marek's disease virus in inoculated chickens. Of the three, EM and FA were the most sensitive in detecting early stages of infection. Virus particles were found in skin biopsy specimens as early as 12 days post inoculation. Immature naked particles appeared first in the nucleus; later particles were enveloped in the cytoplasm and enclosed in cytoplasmic inclusion bodies. No evidence for continued virus replication was seen in feather follicles after an initial burst of heavy virus production, which lasted several weeks. Residual virus, however, was found occasionally in cytoplasmic inclusion bodies within keratinized material near the feathers. This was believed to contribute to the long-term shedding of infectious virus into the environment.

Cellular Responses of Mice to Diffusion Chambers I. Reactions to Intraperitoneal Diffusion Chambers Containing Listeria monocytogenes and to Bacteria-Free Chambers.

Diffusion chambers made with membranes having a pore size of 0.22 mum were implanted in the peritoneal cavities of mice. Chambers that contained no cells induced splenic lymphoreticular hyperplasia and a proliferation of fibroblasts around the chambers. When the chambers contained the bacterium, Listeria monocytogenes, there was strong and continuous chemotaxis of phagocytic cells to the membrane surface. The tendency to incite fibrosis around the chambers containing bacteria produced a tissue reaction resembling a chronic abscess or granuloma. The important difference from a natural lesion was the prevention of direct parasite-host cell interactions. In studies on the pathogenesis of long persisting host-parasite relationships, one might successfully use diffusion chambers to investigate the role of humoral antimicrobial substances as well as the effects of chronic inflammation, with its local concentration of metabolic products and constituents of phagocytic cells. On the other hand, the presence of diffusion chambers in the tissues is an abnormal situation and changes arising from their presence may complicate the interpretations of some experiments.

Cellular immunity of mice infected with Listeria monocytogenes in diffusion chambers.

The importance of bringing live bacteria into intimate contact with macrophages as a prerequisite for establishing cellular immunity was investigated. The bacterium Listeria monocytogenes was shown to replicate and survive in diffusion chambers implanted in the peritoneal cavities of mice. Humoral substances accruing from host responses to diffusing soluble antigens of the microorganism were unable to inactivate the bacteria. The resistance of mice immunized by subcutaneous inoculation of the live organism always exceeded the resistance of mice with Listeria diffusion chamber implants. Animals with sham diffusion chambers were more resistant to a challenge by L. monocytogenes than were normal mice. Host resistance was not significantly different between Listeria diffusion chamber implant groups and sham diffusion chamber implant groups. The results suggested that direct involvement of macrophages with the parasite is necessary to achieve cellular immunity.