Immune system T cells

The immunomodulatory properties of A -THC [48] are likely due to the interaction with CB2 receptors, highly expressed in cells of the immune system (T-cells, B-cells, macrophages). The effect on the immune system of cannabinoid administration appears to be hormesic, and related to the dosage. Indeed, high doses of caimabinoids suppress immune responses, while more physiologically relevant concentrations of cannabinoids result in metabolic stimulation of lymphocytes and in an increase in pro-inflammatory cytokine production rather than immunosuppression. It has been proposed that the immunosuppressive properties of cannabinoids can find application in the treatment of multiple sclerosis. 

Jerrells, T.R. et al., Effects of ethanol consumption on mucosal and systemic T-cell-de-pendent immune responses to pathogenic microorganisms, Alcohol Clin. Exp. Res., 22 (5 Suppl), 212S, 1998. 

T-cells T (thymus derived) cell. These white blood cells, known as T lymphocytes, mature in the thymus and have regulatory immune funcdons. As part of the adapdve (cell-mediated) immune system, these cells can recognize andgens processed by andgen-presendng cells in the context of specific receptors. The cell surface protein CDS is a marker for these cells. 

In the immune system, T- and B-cells undergo apoptosis in many instances of their development, homeostasis, and activation (review Krammer, 2000 Rathmell and Thompson, 2002). Examples include... 

NK cells are important constituents of the primary natural immune system. NK cell function is modulated by the surface expression of MHC molecules. Unlike T cells, NK cells form a first line of defense and kill target cells without prior sensitization. In addition, stimulatory and inhibitory receptors signal and control NK cell function. Therefore, it is plausible that herpesviruses also address this aspect of natural immunity. The status of this emerging field of research is presented in two reviews. An even more recent addition to the field is the recognition of the importance of chemokines, cytokines and their receptors. As expected from a virus which has co-speciated with the host, herpesviruses use this information and divert it to their advantage. For a virus it makes no difference whether the cell itself responds to virus infection, e.g. by apoptosis or any other type of internal cellular antiviral regulation, or whether the reaction is systemic and involves several specialized cells. It is therefore not surprising that viruses have also found principles to avoid induced cell death. 

For peripheral blood mononuclear cells, which are components of the immune system (B cells, T cells and granulocytes), saturable kinetics of riboflavin uptake were proved (Km = 955 nM). Absorption was reduced by the addition of, among others, lumichrome and dinitrophenol. The transport was temperature dependent and sodium independent. During proliferation of these cells, uptake of the vitamin increased four times, although the transporter affinity and their number per cells remained unchanged. This suggested that accumulation of riboflavin in the cells is associated with variable cellular volume (osmolarity of environment) (Zempleni and Mock 2000) (Tables 36.1-36.4). 

T-Lymphocytes (4,5) and other cellular components of the immune system also have equally wide implications in regulation of the normal immune system. The T-lymphocytes play a central role in the body s response to harmful antigens and tumor—host interaction (4). Responses involve antigens derived from vimses, bacteria, parasites, and tumors. T-ceUs also participate in the immune surveillance response, where self-antigens are recognized, but usually sequestered within the cell and, when exposed, become markers of cellular damage. 

Human Immunodeficiency Virus. Human immunodeficiency vims (HIV) causes Acquired Immunodeficiency Syndrome (AIDS), which has no cure. HIV infects the cells of the human immune system, such as T-lymphocytes, monocytes, and macrophages. After a long period of latency and persistent infection, it results in the progressive decline of the immune system, and leads to full-blown AIDS, resulting in death. 

In addition to their endocrine disrupting properties, it must be appreciated that many of the chemicals in question possess more general toxic properties, which may be potentiated by metabolism by the organism. Several PAHs, PCBs and PCDDs are carcinogenic, while certain phthalate esters can enhance the excretion of zinc, potentially leading to zinc deficiency. Zinc, an essential element, plays a vital role in spermatogenesis and mature T-cell production. Deficiency may result in abnormalities of the male reproductive system, depletion of spermatogenesis and suppression of the immune system. 

In addition to antibodies, the immune system also consists of bone-marrow derived lymphocytes, or B cells, and T cells that come from the thymus gland, both of which (indirectly) produce antibodies. These cells, in turn, may be helped by helper cells (= H) and suppressed by suppressor cells (= S). Helper cells may be alarmed as to the presence of antigens by macrophages (= M) that eat the antigens and leave parts of their meal on their cell surface. 

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