Lymphocytes Natural killer cells

IL-2 (Proleukin) is a cytokine that promotes the proliferation, differentiation, and recruitment of T and B lymphocytes, natural killer cells, and thymocytes. Human recombinant IL-2 is designated as rIL-2. rIL-2 binds to IL-2 receptors on responsive cells and induces proliferation and differentiation of T helper cells and T cytotoxic cells. It also can induce B-lymphocyte proliferation, activate macrophage activity, and augment the cytotoxicity of natural killer cells. 

In rat liver, 1,2-dimethylhydrazine had no consistent effect on the relative focal volume of y-glutamyltranspeptidase-positive preneoplastic foci (Denda et al., 1988). Locniskar et al. (1985) treated Brown-Norway and Fischer rats with 150 mg/kg bw 1,2-dimethylhydrazine by gavage five times over a three-week period. Five months after the final treatment, isolated splenic, colonic intraperithelial lymphocytes and lamina propria lymphocytes from the Brown-Norway strain exhibited low natural killer cell activity and reduced splenic T-lymphocyte proliferation in response to autologous non-T lymphocytes. Furthermore, colonic lamina propria lymphocyte proliferation was low, and Brown-Norway rats had a low incidence of 1,2-dimethylhydrazine-induced colonic neoplasms (7%) in comparison with Fischer rats, which had more effective splenic and colonic intraperithelial lymphocyte natural killer cell activity, enhanced splenic autologous mixed lymphocyte response, enhanced colonic lamina propria lymphocyte proliferation and a higher incidence of colon tumours (20%). 

The effects of marijuana on immune function have been reviewed (122). The studies suggest that marijuana affects immune cell function of T and B lymphocytes, natural killer cells, and macrophages. In addition, cannabis appears to modulate host resistance, especially the secondary immune response to various infectious agents, both viral and bacterial. Lastly, marijuana may also affect the cytokine network, influencing the production and function of acute-phase and immune cytokines and modulating network cells, such as macrophages and T helper cells. Under some conditions, marijuana may be immunomodulatory and promote disease. 

Exercise poses a stress on the immune system however, moderate chronic exercise may enhance positive immune functions. Severe or intense long-term exercise may compromise the immune system by suppressing concentrations of lymphocytes, natural-killer cell activity, lymphocyte proliferation, and secretory IgA. During the period of immune impairment ( open window"), microbial agents may invade the host and cause infections. The changes in immune functions, lower exercise capacity, and nutritional factors in the elderly may lead to a greater and longer open window period, increased risk of infections which may contribute to morbidity and mortality. 

Lysis of various target cells coated with antibody by Fc receptor-bearing killer cells, including large granular lymphocytes ( - natural killer cells), neutrophils, eosinophils, and mononuclear phagocytes. 

COPD is a chronic inflammatory disease that results from prolonged and repeated inhalation of particles and gases, chronic (or latent) infection or an interaction of these factors. In many cases, the inflammation persists even when the exposure (in most cases smoking) is stopped. Prominent among the infiltrating leukocytes are neutrophils, CD8+ lymphocytes (Co-receptor for the T-cell receptor. CD8+ is specific for the class IMHC protein. It is expressed on the surface of cytotoxic T-cells and natural killer cells.) and CD68+ monocytic cells (A lysosomal antigen. All cells that rich in... 

Immune Defense. Figure 2 Cytokines involved in the development of adaptive immune responses in secondary lympoid tissues such as the lymph nodes or spleen. Abbreviations B B-lymphocyte, IFN interferon, Ig immunoglobulin, IL interleukin, NK natural killer cell, TE T-effector (cytotoxic) lymphocyte, TH T-helper lymphocyte... 

Syk and ZAP-70 are early intermediates in the transduction of signals from immune receptors, including the B- and T-cell recqrtors for antigen, activatory natural killer-cell receptors, the mast cell and basophil receptor for IgE, and the widely distributed receptors for the Fc portion of IgG. Immune receptors control checkpoints in lymphocyte development and serve to integrate the responses of innate and acquired immunity. 

Studies of the effects of in vitro exposure to a range of concentrations (encompassing environmentally relevant concentrations of monobutyltin, dibutyltin, and tributyltin) on human natural killer lymphocytes obtained from adult male and female donors revealed the presence of detectable concentrations of the butyltins in all the donors, indicating possible exposure of natural killer cells to butyltins in the blood. It was suggested that the study provided evidence that butyltin compounds significantly inhibit natural killer cell function and possible natural killer cell-mediated potential in humans (Whalen etal, 1999). 

Natural killer cell Lymphocytes Rat (prenatal and lactation exposure) Yes Reduced 42% Ilback et al. (1991)... 

IL-1 (17.5) Monocyte/macrophage, lymphocyte, neutrophil, endothelium, fibroblast keratinocyte Activation of T cells, B cells, natural killer cells, osteoblasts, and endothelium. Induces fever, sleep, anorexia, ACTH release, hepatic acute phase protein synthesis and HSPs. Leads to myocardial depression, hypercoagulability, hypotension/sbock, and death. Simulates production of TNF, IL-6, and IL-8 and stress hormone release. Suppression of cytochrome P-450, thyro-globulin, and lipoprotein synthesis. Procoagulant activity. Antiviral activity. 

The CB2 receptor has a more limited distribution, being localized predominantly in the immune system. Among the human leukocytes, B lymphocytes express the highest levels of CB2, followed respectively by natural killer cells, monocytes, polymorphonuclear neutrophils, T8 lymphocytes, and T4 lymphocytes. It is also found in the lymph nodes, spleen, tonsils, and thymus (Cabral, 1999). 

Kimura, A., Orn, A., Holmquist, G., Wizzell, H., and Ersson, B. (1979) Unique lectin-binding characteristics of cytotoxic T-lymphocytes allowing their distribution from natural killer cells and K cells. Eur. J. Immunol. 9, 575. 

Pasqualetti, D. et al., Lymphocyte T subsets and natural killer cells in Italian and Philippino blood donors, Vox Sang., 84, 68, 2003. 

Based upon recent controlled studies, there is considerable evidence that opioids such as morphine induce substantial effects on immune status. For example, it has been shown that morphine administration is associated with alterations in a number of immune parameters, such as natural-killer cell activity [12,13], proliferation of lymphocytes, [13, 14] antibody production [15,16], and the production of interferon [17]. Studies in our laboratory have shown that acute morphine treatment in rats suppresses splenic lymphocyte proliferative responses to both T- and B-cell mitogens, splenic natural-killer cell activity, blood lymphocyte mitogenic responsiveness to T-cell mitogens, and the in vitro production of the cytokines interleukin-2 and interferon-y [18-22], Furthermore, the immune alterations induced by morphine are dose-dependent and antagonized by the opioid-receptor antagonist, naltrexone (e.g., [22]). 

Novick, D.M. et al., Natural killer cell activity and lymphocyte subsets in parenteral heroin abusers and long-term methadone maintenance patients, J. Pharmacol. Exp. Ther., 250, 606, 1989. 

Bonneau, R. H. et al., Stress-induced suppression of herpes simplex virus (HSV)-specific cytotoxic T lymphocyte and natural killer cell activity and enhancement of acute pathogenesis following local HSV infection, Brain Behav. Immun., 5, 170, 1991. 

Merluzzi, VJ. (1985). Comparison of murine lymphokine, activated killer cells, natural killer cells, and cytotoxic T lymphocytes. Cell Immunol. 95 95-104. 

There are two classes of cells those that respond to a specific foreign agent or substance, and those that are not specific. The cells that are specific for a certain foreign agent are lymphocytes. Cells that are not specific for the foreign agent they attack include phagocytes, mast cells, eosinophils, and natural killer cells. 

Immunological and Lymphoreticular Effects. Occupational exposures to inhaled formaldehyde, phenol and isomers of organic chlorohydrocarbons from Ksylamit which is a widely used liquid wood preservative, were associated with immunological effects such as decreased levels of CD4, suppressed mitogen-induced lymphocyte proliferation, and significantly decreased natural killer cell cytotoxicity. However, it should be noted that in the report Ksylamit is indicated to consist of a mixture of chlorinated benzenes, pentachlorophenol, alpha-chloronaphthalene, chloroparaffin and kerosene and that the authors provide no discussion of how phenol and formaldehyde are produced through the use of such a mixture (Baj et al. 1994). 

Robertson, L.E., Denny, A.W., Huh, Y.O., Plunkett, W., Keating, M.J., and Nelson, J.A., Natural killer cell activity in chronic lymphocytic leukemia patients treated with fludarabine, Cancer Chemother. Pharmacol., 37, 1996, 445-450. 

The T-helper cells are further divided into two types, T-helper 1 (ThI) and T-helper 2 (Th2) (see below for discussion). Of the total lymphocyte population in the body (approx. 10 cells), the proportion of T-cells is 50-60%, that of B-cells is 10-15% and that of natural killer cells is <10%. 

Natural killer cells (large granular lymphocytes)... 

There are only two soluble agents involved in killing, antibodies and complement (see above) but there are six types of cells (i) B-lymphocytes, discussed above (ii) cytotoxic T-ceUs (iii) natural killer cells (iv) eosinophils plus mast cells (v) neutrophils and (vi) macrophages. 

When a cell is infected with a virus, the latter utilises the metabolic machinery within the host cell to generate viral proteins, RNA and DNA to produce more virus particles which then escape to infect other cells. The process is stopped by death of the host cells so that generation of new viruses is halted. The major mechanism that results in death of the host cell is apoptosis. The cells that are responsible for the death of the infected cells are either cytotoxic lymphocytes or natural killer cells. Death is caused either by release of toxic biochemicals and/or proteolytic enzymes or by binding to a death receptor, which is present on many cells. The entry of proteolytic enzymes or binding to the death receptor results in activation of initiator caspases. These activate effector caspases that cause damage to the cell which results in death due to apoptosis (Chapter 17 Figures 17.28, 29 and 30). 

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