Immune System Of Rats Research Articles

Effects of ammonia caramel and tetrahydroxybutylimidazole on the immune system of rats.

Caramel (E150) refers to a large number of poorly defined and very complex products used as colourants in human foodstuffs and beverages. It has been demonstrated that oral administration of ammonia caramel (AC; Class III caramel colour) can cause a reduction in total white blood cell counts in rats, due to reduced lymphocyte counts (Evans et al 1977; Gaunt et al 1977; Sinkeldam et al 1988). This lymphopenic effect was found to occur only when the animals were fed a diet low in pyridoxine (vitamin B6) (Sinkeldam et al 1988).

The immune system and opiate withdrawal

Whole body exposure to 500 rad ionizing irradiation suppresses the immune system in rats. Moreover, when administered prior to chronic morphine treatment, irradiation exposure also dramatically reduces the severity of naloxone-precipitated withdrawal in morphine dependent animals. The reinstillment of 2−6 × 10 8 normal lymphoid immunocompetent cells to irradiated rats by adoptive transfer prior to chronic morphine treatment restores all withdrawal signs precipiated by naloxone injection. The data suggest that specific cellular activities or factors derived from lymphoid cells are required for the expression of opiate withdrawal, indicating that the immune system participates in the manifestation of opiate dependence.

Failure to Detect Immune Deficiency in Rats after Prenatal or Early Postnatal Irradiation

We have looked for medium-term sequelae in the immune system of rats that had been X-irradiated (0-2 Gy whole-body irradiation) during prenatal or early postnatal life. At an age of 8 weeks the histology of the spleen was normal, and so was the distribution of B and T lymphocytes. The serum immunoglobulin levels were not significantly altered, even when the different isotypes were considered. At an age of 10 weeks, the rats were immunized with a T-dependent or a T-independent dinitrophenylated-carrier antigen. Normal levels of specific antibodies were generated in all groups of animals injected with the T-independent antigen. The T-dependent response, in contrast, was higher in animals irradiated between day 6 and day 20 of gestation (but not in rats irradiated early after birth). This increase, however, was significant only for the IgM and IgG1 responses of some irradiated groups. Thus no medium-term immunodeficiency could be documented with the methods used. The alteration in a T-dependent response, however, points to a radiosensitive T regulatory mechanism.

Effect of 2,5-hexanedione on lymphoid organs of rats: A preliminary report

Preliminary studies related to immunotoxicologic effects of 2,5-hexanedione, the final major metabolite of n-hexane/MnBk, were carried out in rats following single or repeated exposures. Female albino rats were given either single or seven consecutive oral doses of 0.1, 0.2, or 0.5 X LD50 of 2,5-hexanedione, and a time-related kinetic study was performed using hematology, histology, cellularity, and organ weight/body weight as major parameters. Following single exposure of 2,5-hexanedione to rats, a dose-dependent thymic atrophy was evident at the end of 7 days. The atrophy was reversible when the animals were given 7 days nonexposure rest. In contrast, there was no thymic atrophy when the animals were exposed for 7 consecutive days. Significant decline in the cellular populations of various lymphoid organs was also observed in rats exposed either to single or repeated doses of 2,5-hexanedione. Results obtained in the present study indicate that 2,5-hexanedione, a known potent neurotoxic substance, adversely affects the lymphoid organs of the immune system in rats.

Effects of trimethyltin on the immune system of rats

Treatment with trimethyltin (TMT) induced atrophy of the thymus, spleen and lymph nodes within 2 days, but no changes in the bone marrow were observed. Atrophy of thymus and spleen did not occur in adrenal-ectomized rats treated with TMT. Antibody responses to sheep erythrocytes (SRBC) and proliferative responses of spleen lymphocytes to phytohemagglutinin (PHA), concanavalin A (ConA) and lipopolysaccharides (LPS) were suppressed significantly in treated rats. Delayed hypersensivity to oxazalone, natural killer (NK) cell activity and the phagocytic activity of peritoneal macrophages (PEM) were not affected significantly.

Effects of coal dust and diesel exhaust on immune competence in rats.

The effects on the immune system of rats that had been exposed to a 2-mg/m3 dose of either respirable coal dust, diesel exhaust fumes and particulates, or the combination of these were studied. Animals that were housed similarly but exposed only to filtered air served as controls. After 12 and 24 mo of exposure, the rats were tested for immunocompetency by enumerating antibody-producing cells in the spleen 4 d after immunization with sheep erythrocytes and by monitoring the proliferative response of splenic T-lymphocytes to the mitogens concanavalin A and phytohemagglutinin. The results of this study indicate that no major alterations occurred in the immunologic functions measured as a result of exposure to either coal dust, diesel exhaust fumes and particulates, or their combination.

Spontaneous diabetes mellitus syndrome in the rat. III. Pancreatic alterations in aglycosuric and untreated diabetic BB Wistar-derived rats

The pancreatic alterations in aglycosuric and untreated diabetic BB Wistar-derived rats are described. A common finding, often seen in young aglycosuric rats, is that of discrete foci of periductular and/or acinar aggregates of lymphocytes and macrophages. Sites of periductular mononuclear cell infiltrates usually lack endocrine cells. In contrast, foci of acinar infiltrates, although distinct from the predominant endocrine cell mass in the islets of Langerhans, often contain small numbers of alpha and/or beta cells. It is suggested that these clusters of endocrine cells may in some way be antigenically different from those resident in the principal islets and thus serve as an additional target for the immune system in rats bearing the BB genome. The development of overt diabetes requires a massive destruction of beta cells within the islets of Langerhans. Two forms of diabetes mellitus emerge in untreated animals. The more common, designated unstable diabetes, is severe and lethal unless treated with insulin. Less commonly, a stable type of diabetes mellitus ensues for which insulin therapy is not mandatory. In each, the concentration of pancreatic immunoreactive insulin is profoundly decreased, although relatively greater amounts are present in the stable form. Unstable diabetic rats demonstrate a reduction in the concentration of pancreatic immunoreactive glucagon and somatostatin, suggesting that alpha and delta cells also sustain injury in this model of insulin-dependent diabetes mellitus.

Induction of expression of the rat G5 nervous system antigen occurs postnatally

G5 is a cell membrane component found in high levels in the adult rat central nervous system and in low levels on some cells of the rat immune system. Binding assays with adult brain particulate protein preparations and monoclonal antibody to G5 (G5-IgG) gave highest activity in cerebral cortex and lowest in the white matter rich regions pons and spinal cord. Three peripheral nervous system components had no G5 activity. Analysis of G5 content in particulate protein preparations from whole rat brain of ages embryonic day 15 to adult indicates that G5 is present in negligible amounts in the newborn rat. It increases in both specific and total activity to reach adult levels by postnatal day 30. A similar induction curve was observed with cerebellum samples. In adult cerebellum, high levels of G5 were found in the molecular layer using both autoradiographic and immunofluorescence techniques. White matter had essentially no activity. The density and uniformity of reaction product in these techniques suggest that G5 is present on a major cellular constituent of the molecular layer. Pharmacologic experiments indicate G5 is not detectable on climbing fibers on adrenergic fibers. Cerebellar samples from juvenile rats also had predominant G5 activity in the forming molecular layer.

Effect of Hexachlorobenzene on the Immune System of Rats Following Combined Pre- and Postnatal Exposure

ABSTRACTThe effect of HCB on the immune system was studied after combined pre- and postnatal exposure. Pregnant rats received diets containing 50 and 150 mg HCB/kg. Dosing continued during lactation and after weaning. At an age of 5 weeks the immune system was functionally assessed. in both treatment groups, the resistance to L.mono-cytogenes infection was suppressed, as was the resistance to an infection with T. spiralis (increased yield of muscle larvae). No effect was observed on allograft rejection or on mitogenic response of thymus and spleen cells. HCB enhanced the thymus-dependent antibody response to T.spiralis antigen and to tetanus toxoid (secondary IgG titers to tetanus toxoid were increased 16-fold in both test groups). No effect was found on the thymus-independent IgM response to LPS, on the passive cutaneous anaphylaxis and on the clearance of carbon particles and L.monocytogenes. HCB treatment caused morphologic changes in lymph nodes, lung and liver. It is concluded that HCB suppresses cel...

The effect of chronic alcohol administration on the immune responsiveness of rats

A series of studies were carried out to determine the effect of chronic alcohol administration on cellular and humoral immunity in the rat. Alcohol-treated rats received an alcohol liquid formula diet for 3 months, and this uniformly resulted in the development of a fatty liver. In alcohol-treated rats there was a delay in antibody production to both typhoid H and B. abortus antigens following a primary immunization. The peak titers obtained, however, were not significantly different from those of the control animals. The secondary response to typhoid H antigen was not affected. The expression of cutaneous delayed hypersensitivity to a potent skin sensitizing chemical, 2, 4-dinitrofluorobenzene, was also depressed in alcohol-treated rats. Animals receiving alcohol also had markedly atrophic thymuses and small spleens. The normal thymuses and adrenal glands found in control animals treated with ACTH injections indicate that the changes were not due to hyperactivity of the adrenal cortex in a stressful situation. It is postulated that the deleterious effects of alcohol on the immune system of rats may be due to alteration in either reticuloendothelial or thymic function.

Marginal zone and germinal center development in the spleens of neonatally thymectomized and nonthymectomized young rats.

AbstractSpleens from neonatally thymectomized and nonthymectomized young rats were studied histologically and histochemically to elucidate the development of the splenic immune system with and without thymus.In intact animals primitive germinal center activity could be elicited with antigen as early as 13 days of age. More definitive germinal centers lacking tingible body macrophages were observed at 18 days of age. Germinal centers containing tingible body macrophages did not develop until 35 days of age in response to antigenic stimulation. This coincided with maximal development of the marginal zone of medium‐sized lymphocytes and the mature development of nodular macrophages possessing strong acid phosphatase activity.Neonatally thymectomized rats developed marginal zones and germinal centers similar to control littermates when the young animals were maintained on tetracycline. Thymectomized animals not given tetracycline showed disturbances in splenic development. These are discussed.The results suggest that the thymus may be critical to the immune system in rats from birth to about 30 days of age but is not essential to its function beyond this period. Marginal zone lymphocytes and germinal center cells proliferate normally and mature to the plasma cell stage in the absence of a thymus if the animals are maintained on tetracycline beyond this critical age.