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Results for “Immune function”

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At least 1,549 records · Page 86Linked to original sources
PubMed1997

The effect of beta-carotene supplementation on the immune function of blood monocytes from healthy male nonsmokers.

Although there is strong epidemiologic evidence that diets rich in carotenoids such as beta-carotene are associated with a reduced incidence of cancer, the cellular mechanisms underlying this phenomenon remain unknown. This article describes the effect of dietary beta-carotene supplementation on both the expression of functionally associated surface molecules on human monocytes and on the secretion of the cytokine tumor necrosis factor-alpha (TNF-alpha) by monocytes, all of which are involved in the initiation and regulation of immune responses involved in tumor surveillance. A double-blind, placebo-controlled, crossover study was undertaken in which 25 healthy, adult male nonsmokers were randomly assigned to receive beta-carotene (15 mg daily) or placebo for 26 days, followed by the alternative treatment for a further 26 days. The expression of functionally related monocyte surface molecules was quantified by flow cytometry, and ex vivo secretion of TNF-alpha was quantified by an enzyme-linked immunosorbent assay, before and after each treatment period. After dietary supplementation there were significant increases in plasma levels of beta-carotene and in the percentages of monocytes expressing the major histocompatibility complex class II molecule HLA-DR and the adhesion molecules intercellular adhesion molecule-1 and leukocyte function-associated antigen-3. In addition, the ex vivo TNF-alpha secretion by blood monocytes was significantly increased after supplementation. These findings suggest that moderate increases in the dietary intake of beta-carotene can enhance cell-mediated immune responses within a relatively short period of time, providing a potential mechanism for the anticarcinogenic properties attributed to beta-carotene.

Adult↗
PubMed1994

Influence of dietary restriction and soyabean supplementation on the growth of a murine lymphoma and host immune function.

A comparative study was made to reveal the influence of caloric restriction with or without soyabean in the diet on the growth of a murine lymphoma, host survival, serum profile of vitamin A and E and immune status of the host. Caloric restriction delayed and inhibited tumour growth and improved host survival; inclusion of soyabean during restriction enhanced this effect. Dietary restriction both in the absence and presence of soyabean improved the proliferative response of peripheral blood lymphocytes. This was accompanied by increased cytolytic activity of peritoneal macrophages and elevation in serum immunoglobulins (IgG and IgM). Levels of vitamins A and E, which is found to be low in tumour bearing animals, decreased further when maintained in the restricted diet without soyabean, but was raised to normal levels following addition of soyabean in the diet. These observations imply that tumour growth is arrested possibly by insufficient nutrition available due to dietary restriction, for actively proliferating tumour cells and by improvement in host immune mechanism in the presence of soyabean in the diet.

Animals↗
PubMed1984

Interference in general immune function by parasite infections; African trypanosomiasis as a model system.

Many parasitic diseases are accompanied by an immunosuppression which may affect only parasite-specific responses in some infections or lead to a general dysfunction of the immune system in others. African trypanosomiasis causes a particularly severe disorder of the immune system and this serves as a model system for analysis of the cellular basis of a parasite-induced general immune dysfunction affecting nearly all T- or B-lymphoid cell subpopulations. The nature of the parasite products causing havoc in the immune system may well vary in different infections and still remains to be defined. Trypanosome membrane fractions are active in vitro or in vivo but we have no evidence for a direct action on B- or T-cells. In vitro, both in man and mouse, T-cells are stimulated, but only in the presence of accessory cells. This points to the importance of host-derived immunosuppressive factors in the immune dysfunction. We have evidence that macrophages, after uptake of parasites in the presence of antibodies, are at least one target cell for parasite action. They can mediate immunosuppression and undergo changes in phenotype and mediator release during the course of infection. The macrophages show all the characteristic signs of activation, which can also be induced by other means and other infective agents such as BCG. Thus, macrophage activation would provide a common pathway for induction of a general immunosuppression in different infections.

Animals↗
PubMed1994

The effects of kainic acid-induced lesions in the lateral septal area on cell-mediated immune function.

The lateral septal area (LSA) is a primary control region for psychoneuroendocrine functions, and we have previously reported that kainic acid (KA) lesions in the LSA and the hippocampus have inhibitory and facilitatory effects, respectively, on the humoral immune response of female rats. Thus, these limbic structures may selectively participate in directing neuroimmune regulation. In order to assess the fundamental role of the LSA in neuroimmune regulation, we have evaluated the effects of neurotoxic septal lesions on various cell-mediated immune measures. Animals received stereotaxically guided bilateral infusions of KA (2.0 micrograms/microliter) or physiological saline (SHAM) into the LSA. Following a 2-week recovery period, animals were sacrificed and the spleen cells analyzed for natural killer (NK) cell activity and T-cell responsiveness to mitogen (ConA) or to anti T-cell receptor mAb (R73). A separate group of LSA-lesioned animals were immunized with sheep red blood cells 4 days prior to harvesting the spleen for plaque forming cell (PFC) number determination and measurement of TNF-alpha secretion from splenic macrophages. The results indicate that rats with KA lesions in the LSA have significantly higher NK cell activity, significantly lower numbers of splenic PFCs, and significantly reduced TNF-alpha secretion from splenic macrophages, relative to controls. There was a statistical tendency (p < .1) for reduced T-cell lymphoproliferative responses to ConA stimulation in LSA-lesioned animals, relative to SHAMs. However, the T-cell lymphoproliferative response to specific activation via the T-cell receptor was not significantly different between lesioned and control groups. These results further demonstrate the importance of KA-sensitive LSA neurons in neuroimmunoregulation. Moreover, selective alterations of different components of the immune system are observed in LSA-lesioned animals, suggesting that the LSA is involved in the complex and differential regulation of immunity.

Animals↗
PubMed2000

Early highly active antiretroviral therapy for acute HIV-1 infection preserves immune function of CD8+ and CD4+ T lymphocytes.

Highly active antiretroviral therapy (HAART) has been advocated for the management of primary HIV-1 infection without clear understanding of its immunological effects. Here, we demonstrate that early use of HAART during primary infection preserves HIV-specific CD8(+) T cells physically and functionally while HIV-specific T cell help is sustained. We also show that even transient administration of HAART at seroconversion can preserve HIV-specific immunity. In contrast, delayed initiation of HAART is associated with a progressive loss of HIV-specific CD8(+) T cells and absent HIV-specific T cell help. These results imply that HIV-specific T help is damaged during primary HIV-1 infection. Early drug treatment, which preserves this immunity, also preserves HIV-specific CD8(+) T cells. These results have implications for understanding the early pathogenesis of HIV-1 infection and suggest that acute HIV infection should be treated aggressively and as early as possible.

Amino Acid Sequence↗
PubMed1987

Modulation of immune function in cancer patients.

This paper will focus on three aspects of work which we have conducted in our laboratory over the past several years. Firstly, it will present results of studies in which we have found a selective inhibition of suppressor cell function in solid tumor cancer patients treated with cytotoxic drugs. Secondly, it will show that this selective inhibition results in an augmentation of other forms of immune reactivity and, in particular, an enhanced interleukin-2 production and response to this. Finally, it will demonstrate how we have made use of that information to intervene pharmacologically to modulate the immunosuppression which usually follows the use of cytotoxic drugs in solid tumor cancer patients.

Antineoplastic Agents↗
PubMed1993

European isolation and confinement study. Confinement and immune function.

During spaceflight, several unusual factors act on the physiology of the astronaut: weightlessness, radiation, confinement, isolation, living and working in a small group, workload, and anxiety. The resulting physiological changes are known to include alterations of the immune system. It is difficult to determine from observations on astronauts which space-related factor(s) are responsible for the immune changes. Studies of analogous environments on Earth have supplied only scarce information. Dedicated simulation studies provide a better tool, where some space-related stress factors (weightlessness, radiation) are absent, but others are or can be present: isolation and confinement, small group living, workload, and anxiety. A reduction in immune activity was found in bed rest studies and in long-term Soviet confinement experiments (after 90 days). In the ISEMSI confinement experiment (28 days), a tendency to immune activation (PHA-reactivity and interleukin-2 production) was observed in two out of six subjects. There is a need for further experiments, in which a large number of immunological parameters can be analyzed.

Humans↗
PubMed1987

Failure of TPN supplementation to improve liver function, immunity, and mortality in thermally injured patients.

Hypermetabolism with negative nitrogen balance and immune deficiencies characterize the systemic response to major thermal injury. Patients with burns greater than 50% of the total body surface area (TBSA) initially have poor gastrointestinal function, making it difficult to deliver sufficient enteral calories to meet nutritional requirements. Controversy has developed over whether to supplement oral alimentation with total parenteral nutrition (TPN) early in their treatment. This study randomly assigned 28 patients with burns greater than 50% TBSA to receive TPN supplementation or no TPN supplementation in the first 10 days postburn. Patients receiving TPN supplementation had significantly lower T-cell helper-to-suppressor cell ratios than the unsupplemented group. However, there was no difference in mortality between the groups (eight in each). All patients who died developed hepatomegaly associated with fatty infiltration cholestasis and antemortem liver function abnormalities, indicating that this syndrome is the result of burn injury itself, not TPN.

Adult↗