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The avian immune system is reviewed. The avian immune system differs from that of mammals, mainly in the presence or absence of lymphoid organ and in the histology of these organs, in the antibody response, in the generation of diversity of antibodies, and in the transfer of maternal immunity. The chicken immune system is mainly discussed, since most of the research on the avian immune system has been performed using this bird.
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A direct comparison of systemic (spleen) and mucosal (intestine) antibody-producing systems was made in weanling male C57BL/6J mice subjected to wasting protein-energy malnutrition (PEM) by means of a low-protein protocol known to duplicate immunological and physiological features of human malnutrition. ELISA revealed low concentrations of biliary and gut lumen immunoglobulin (Ig) A in malnourished mice concomitantly with a high concentration of blood IgA. The low-protein model, therefore, exhibited fidelity to human protein-energy malnutrition in its influence on the concentrations of the mucosal Ig, IgA, in critical biological fluids. The number of IgA-, IgM- and IgG-containing cells was estimated morphometrically on a per organ basis. The low-protein protocol supported expansion in numbers of mucosal IgA-containing cells (18 x relative to a zero-time control group) and of splenic IgG-containing cells (135x), albeit an attenuated expansion in comparison with that of well-nourished control animals (132x and 571x respectively relative to zero-time controls). Up to terminal differentiation of Ig-containing cells, systemic and mucosal antibody-producing systems exhibited similarly remarkable resistance to wasting malnutrition. Epithelial transport of IgA may be an aspect of the mucosal antibody response which is particularly sensitive to PEM.
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T-cell receptor (TCR) with unique major histocompatibility complex (MHC)-unrestricted antigen-binding properties was isolated from a human T-cell clone specific for the tumor antigen MUC1. This TCR binds its epitope on the MUC1 protein without the requirement of processing and presentation. A single-chain Valpha/Vbeta/Cbeta (scTCR) was fused to a CD3 zeta (zeta) chain to allow expression on the surface of cells of the innate (granulocytes, macrophages, natural killer [NK] cells) as well as the adaptive (T and B cells) immune system. To test the ability of the cells of the innate immune system to reject a tumor when provided with a tumor antigen-specific TCR, we reconstituted severe combined immunodeficiency (SCID) mice with bone marrow cells transduced with a retroviral vector encoding this receptor and challenged them with a MUC1-positive human tumor. These mice controlled the growth of the tumor significantly better than the control mice. We performed a similar experiment in immunocompetent mice transgenic for human MUC1. Expression of the TCR on large percentages of cells did not result in infiltration or destruction of tissues expressing MUC1. Reconstituted mice controlled the outgrowth of a MUC1-transfected but not the parental control tumor. scTCR expression appears lifelong, suggesting a successful transduction of the self-renewing stem cells.
The immune system consists of organs and several cell types. Antigen interaction with these cells induces a cellular immune response mediated by activated cells and a humoral immune response mediated by antibodies. The cellular interactions are enhanced by adhesion molecules, and the activated cells release different cytokines. These complex cellular interactions induce a systemic immune response. If the antigen penetrates by the oral route, a secretory immune response is obtained, which is mediated by secretory IgA. The determination of the number of T or B cells, the quantitative or qualitative measure of the cytokines, antibody levels, or the study of cellular function such as phagocytic activity is used to evaluate the state of the immune system. The effects of lactic acid bacteria on the systemic immune response and on the secretory immune system are described. Potential health benefits of lactic acid bacteria include protection against enteric infections, use as an oral adjuvant, the immunopotentiator in malnutrition, and the prevention of chemically induced tumors. The results showed that Lactobacillus casei could prevent enteric infections and stimulate secretory IgA in malnourished animals, but could produce bacteria translocation. Yogurt could inhibit the growth of intestinal carcinoma through increased activity of IgA, T cells, and macrophages.
The catecholamines norepinephrine and epinephrine are used by the sympathetic nervous system to communicate with other organ systems, including the immune system. Adrenergic receptors on target cells bind these catecholamines and modulate the activity of the target cell. The beta 2-adrenergic receptor is the most abundantly expressed and best studied adrenergic receptor in the immune system. Here, I summarize data from our own laboratory and from others on the expression and possible function of alpha 1-adrenergic receptors in the immune system. alpha 1-Adrenergic receptor expression in the immune system can be regulated by glucocorticoids, by beta 2-adrenergic agonists, and by cytokines. In addition, the possible pathophysiological implications of the expression of alpha 1-adrenergic receptors on immune cells from arthritis patients are discussed.
The effects of an orally administered hot-water extract (HW) from cultured mycelia of Cordyceps sinensis on the activation of macrophages and the intestinal immune system were studied in mice. The general composition of HW was 83.9% carbohydrate, 11.8% protein, 1.9% lipid and 2.4% ash, and the carbohydrates were mainly composed of glucose, mannose, galactose and arabinose (molar ratio of 1.0:0.8:0.5:0.1). HW stimulated the activation (1.7-fold of the saline control) of macrophages and IL-6 production (1.5-fold) at 2.0 g/kg/day. Analyzing the culture supernatant of Peyer's patch cells from C3H/HeJ mice that had been fed with HW at 1.0 g/kg/day for 7 days indicated that the bone marrow cells had significantly proliferated (1.9-fold). In addition, the amounts of GM-CSF and IL-6 in the culture supernatant of Peyer's patch cells at the same dose were significantly increased (1.8-fold and 2.2-fold, respectively). These results indicate that an oral administration of HW may modulate IL-6 production by the activation of macrophages, and also enhance the secretion of hematopoietic growth factors such as GM-CSF and IL-6 from Peyer's patch cells. Since such cytokines as GM-CSF and IL-6 from Peyer's patch cells act on the systemic immune system, it can be assumed that orally administered HW modulated not only the local but also systemic immune system.
The function of the immune system is known to decline in the elderly. The present communication will show that, similar to the situation in children, it is necessary to distinguish between primary and secondary alterations of the immune reactivity in the elderly. The primary immunological change in the elderly is the age-dependent intrinsic decline of immune responsiveness that is also observed in healthy persons, i.e., those selected according to the criteria of the SENIEUR Protocol of EURAGE (European Community Concerted Action on Aging). Secondary immunological changes are due to underlying diseases and various environmental factors, including diet, drug intake, physical activity, etc. While primary immunodeficiencies of the elderly are not, or only to a very minor extent, presently influenced by therapeutic measures, secondary alterations of the immune function offer further possibilities for corrective measures. Clinically, the consequences of impaired immune function in the elderly include increased susceptibility to infectious disease, the emergence of tumors, and increased autoimmune reactions, the latter albeit often without concomitant autoimmune disease. In fact, autoimmune diseases in generally begin to develop at younger ages, but their consequences are major factors affecting the quality of life of the elderly. Investigations of basic molecular and cellular aspects of the aging immune system are, therefore, of theoretical, clinical and socioeconomic interest.
Degeneracy in the immune system not only refers to the recognition by its specific receptors, but also at the level of functional degeneracy of reactivity by its lymphocytes. Features of the immune system such as dominance and competition occur at each of these two levels. Another characteristic of the immune system as a fuzzy system, is its continuum of states, where difficult choices lead to the emergence of unpredictable phenotypes.
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Prior to the immunization of children aged 3-7 years with parotitis vaccine the state of their immune system was evaluated by the determination of the concentration of IgM, IgG and IgA, the ratio and absolute numbers of T- and B-lymphocytes, the intensity of the blast transformation of lymphocytes. This study revealed that the group of immunized children was essentially heterogeneous with respect to the state of their immune system: in 79.9% of the children all immunological characteristics were normal, in 20.1% of the children some deviations from the characteristics considered to be normal for their age (gammopathy, eosinophilia, the deficiency of T- and B-lymphocytes, a decrease in the intensity of their blast transformation, the leftward shift of the leukocytic formula) were noted. The intensity of humoral immune response in children with deviations from normal characteristics peculiar to their age was significantly lower than in children with normal immunological characteristics. On the basis of these results, the immunological rehabilitation of the risk group among the children to be immunized is recommended.
Recently a lot of studies have pointed to the relationships between the major homeostatic systems of the human body: the neuroendocrine system and the immune system. There is considerable evidence that they make up a psychoneuroendocrine immunologic network. In the present review the most interesting data concerning the relationships between the neuroendocrine system and the immune system are taken into account.
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It is estimated that Helicobacter pylori infects the stomachs of over 50% of the world's population and if not treated may cause chronic gastritis, peptic ulcer disease, gastric adenocarcinoma and gastric B-cell lymphoma. The aim of this study was to enhance the mucosal and systemic immune responses against the H. pylori antigens cytotoxin-associated gene A (CagA) and neutrophil-activating protein (NAP), through combinations of mucosal and systemic immunizations in female BALB/c mice. We found that oral or intranasal (i.n.) followed by i.m. immunizations induced significantly higher serum titres against NAP and CagA compared to i.n. alone, oral alone, i.m. alone, i.m. followed by i.n. or i.m. followed by oral immunizations. However, only oral followed by i.m. immunizations induced anti-NAP antibody-secreting cells in the stomach. Moreover, mucosal immunizations alone or in combination with i.m., but not i.m. immunizations alone, induced mucosal immunoglobulin A (IgA) responses in faeces. Any single route or combination of immunization routes with NAP and CagA preferentially induced antigen-specific splenic interleukin-4-secreting cells and far fewer interferon-gamma-secreting cells in the spleen. Moreover, i.n. immunizations alone or in combination with i.m. immunizations induced predominantly serum IgG1 and far less serum IgG2a. Importantly, we found that while both i.n. and i.m. recall immunizations induced similar levels of serum antibody responses, mucosal IgA responses in faeces were only achieved through i.n. recall immunization. Collectively, our data show that mucosal followed by systemic immunization significantly enhanced local and systemic immune responses and that i.n. recall immunization is required to induce both mucosal and systemic memory type responses.
The data on the central mechanisms of the immune system regulation and the role of opioid peptides in this process are summarized. The fact that the opioid component is involved in the regulation of the system of immunity predetermines the possibility of the influence on the immune system by means of the compounds possessing the opioid activity. This fact and also their low toxicity make the compounds promising for the development on their basis of original immunomodulators devoid of the disadvantages being intrinsic to the available drugs.