T cell, helper

A recent example of a CA model of the immune response in AIDS is Pandley s four-cell model using interactions among macrophages (= M) containing parts of the virus on their surface, helper T cells (= H), cytotoxic T cells (= C) and the virus (= V) ([pand89], [pandQl]) ... 

Stauffer [stauff92] reports that the concentration of cells in this system quickly saturates. For low initial concentrations po, the viral population wins over the population of cells of the immune system and the system can be said to develop Aids. For larger po, the population of helper T cells becomes greater than that of the virus and the immune system wins. 

More complex models must carefully consider additional factors such as the receptor structure of helper T cells and allow for, what in reality, is a less than perfect lock and key match between antibody and antigen. For the latter case, Stauffer [staufF92] describes two schemes in which more than one type of antibody fits a given antigen and more than one type of antigen corresponds to a given antibody. 

Interleukin 2 (IL-2) is a 15.5 kDa glycosylated protein produced by helper T-cells in response to an antigen and interleukin-1. Ligation of the IL-2 receptor (expressed by a number of lymphocytes) by IL-2 stimulates growth, differentiation and survival. 

Helicobacter Pylori Helix Bundle Helix-loop-helix Motif Helper T Cells Hemangioblast Hematopoiesis... 

Mosmann TR, Cherwinski H, Bond MW. Giedlin MA, Coffman RL Two types of murine helper T cell clone. I. Definition according to profiles of lym-phokine activities and secreted proteins. J Immunol 1986 136 2348-2357. 

These are supplied by the secretion of peptide molecules (termed cytokines or lymphokines) fiom a subset of the T-cell family (the helper T cells, TH cells). These peptide molecules (interleukins (IL) 2,4,5 and 6) stimulate the B cells to proliferate, undergo clonal expansion and mature into plasma cells which secrete antibody and also into the longer-hving, non-dividing memory cells. 

The intestinal mucosa of patients with CD has a preponderance of CD4-+- type 1 helper T cells, while patients with UC have more CD4+ lymphocytes with atypical type 2 helper T cells.9 Likewise, drugs such as non-steroidal anti-inflammatory drugs (NSAIDs) that disrupt the integrity of the GI mucosa may facilitate mucosal entry of intestinal antigens and lead to disease flares in patients with IBD.11... 

The inflammatory response in UC is propagated by atypical type 2 helper T cells that produce proinflammatory cytokines such as interleukin-1 (IL-1), IL-6, and tumor necrosis factor (TNF).7 As discussed previously, a genetic predisposition to UC may partially explain the development of excessive colonic and rectal inflammation. The finding of positive perinuclear antineutrophil cytoplasmic antibodies (pANCA) in association with the human leukocyte antigen (HLA)-DR2 allele in a large percentage of patients with UC supports this theory.4,12... 

Helper T cells (CD4+) are the great communicators of the immune response. Once activated, they proliferate and secrete cytokines that regulate effector cell function. Some helper T cells secrete cytokines that recruit cytotoxic T cells, B cells, or APCs, whereas others secrete cytokines that turn off the immune response once an antigen has been destroyed. 

HIV is relatively effective, but it is unable to completely clear the infection, and the patient enters a latent, asymptomatic or mildly symptomatic stage lasting 5 to 15 years. During this time, a high rate of viral replication can be seen in the lymph nodes. Eventually immune deficiency occurs when the body is no longer able to replenish helper T cells at a rate equal to that at which HIV is destroying them. 

Swain SL. Regulation of the development of helper T cell subsets. Immunol Res 1991 10 177-182. 

Breitfeld D, Ohl L, Kremmer E, et al. Follicular B helper T cells express CXC chemokine receptor 5, localize to B cell follicles, and support immunoglobulin production. J Exp Med 2000 192 1545-1552. 

Vinuesa CG, Tangye SG, Moser B, Mackay CR. Follicular B helper T cells in antibody responses and autoimmunity. Nat Rev Immunol 2005 5(ll) 853-865. 

Wang CR, Chen PC, Liu MF. Increased circulating CCR3+ type 2 helper T cells in house dust mite-sensitive Chinese patients with allergic diseases. Asian Pac J Allergy Immunol 2003 21(4) 205-210. 

In spite of having no intrinsic catalytic domains, activation of T lymphocytes commences with tyrosine phosphorylations, activation of PLC-v with production of IP3 and DAG, and elevation of cytosolic free Ca2+. Thus, the consequences of receptor ligation are not dissimilar from those induced by the receptors for EGF or PDGF. An early study trying to explain the induction of tyrosine kinase activity resulted in the discovery of the nonreceptor protein tyrosine kinase Lck (p56lck), a T-cell-specific member of the Src family. Lck is associated with the cytosolic tail of CD4 (in helper T cells) or CD8 (in cytotoxic T cells) (Figure 8.14). As mentioned, the extracellular domains of these... 

Mosmann, T.R. and Coffman, R.L. (1989) Heterogeneity of cytokine secretion patterns and functions of helper T cells. Advances in Immunology 46, 111-147. 

Pond, L., Wassom, D.L. and Hayes, C.E. (1989) Evidence for differential induction of helper T cell subsets during Trichinella spiralis infection. Journal ofImmunology 143, 4232-4237. 

Recently in a study of long-term Li+ patients, the levels of neutrophils, helper T-cells, -lymphocytes, and NK cells were all significantly higher than normal, indicating that these, generally favorable, quantitative changes in leucocyte populations persist with Li+ therapy [207]. 

Vega, L. et al., Helper T cell subpopulations from women are more susceptible to the toxic effect of sodium arsenite in vitro, Toxicology, 199, 121, 2004. 

Cher, D.J. and Mosmann, T.R., Two types of murine helper T cell clones. II. Delayed type hypersensitivity is mediated by Thl clones. J. Immunol., 138, 3688, 1987. 

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