Th 1 cell

A second population of Th-cells, Th-2, regulates B-cell responses (see below) by secreting a different set of cytokines including IL-4, IL-5, IL-6, IL-10, or IL-13. 

In 2006, another subset of Th cells was recognized, known as Thl7 cells [89]. These cells have been described to exert major functions in induction of tissue inflammation and... 

In addition to binding of FceRII at the surface of B cells, IgE also binds FceRI at the surface of DCs and monocytes. This process increases the uptake of allergen by DCs and the subsequent presentation to specific Th cells, which drive the late phase of the allergic inflammation [3,144]. 

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. 

Antigens requiring the assistance of TH cells are termed T-dependent (TD) antigens. 

Some antigens, such as type 3 pneumococcal polysaccharide, EPS and other polymeric substances such as dextrans (poly-D-glucose) and levan (poly-D-fructose) can induce antibody synthesis without the assistance of TH cells. These are known as T-independent (Ti) antigens. Only one class of immunoglobulin (IgM) is synthesized and there is a weak memory response. 

Infection with a human immunodeficiency virus (HIV-1 and HIV-2 see Chapter 3) can cause the destruction of the TH cell, which is the eritieal eell of the immune system. This leads to the condition known as acquired immune deficieney syndrome (AIDS). At present, it is still not known why, in some cases, infection with HIV leaves the immune system intact whereas in others it is irreversibly destroyed, giving rise to AIDS. 

Like TH cells, two signals are required to activate the Tc cell. The first is an interaction between the TCRs and the Class 1 MHC molecule/foreign epitope complex on the surface of the target cell. The second signal is that of IL-2 produced by the activated TH cell with the resultant release of cytotoxins which destroy the target cell. 

T-suppression. Ts cells may be activated more effectively than TH cells, thereby suppressing the immune response. 

D Ambrosio D, Iellem A, Bonecchi R, et al. Selective up-regulation of chemokine receptors CCR4 and CCR8 upon activation of polarized human type 2 Th cells. J Immunol 1998 161 5111-5115. 

Grencis, R.K, Hiiltner, L. and Else, K.J. (1991) Host protective immunity to Trichinella spiralis in mice activation of Th cell subsets and lymphokine... 

Else, KJ., Hultner, L. and Grencis, R.K. (1992) Cellular immune responses to the murine nematode parasite Trichuris muris. II. Differential induction of TH-cell subsets in resistant versus susceptible mice. Immunology 75, 232-237. 

Before consideration of the available methods, what is known of the immunobiological mechanisms of both forms of chemical allergy will be reviewed briefly. The development of immune responses, including allergic responses, is directed by the activity of CD4+ T helper (Th) cell subpopulations and their cytokine products. Two phenotypes... 

The estimation of statistical quantities for each cell is straightforward. For example, the estimated scalar mean in the /th cell is just... 

The mechanisms of autoimmunity may also entail interaction with MHC structures determined by the HLA alleles. Individuals carrying certain HLA alleles have been shown to be predisposed to certain autoimmune diseases, which may account in part for the genetic variability of autoimmunity. In addition, metabolites of a particular drug may vary between individuals to confound the development of drug-induced autoimmunity. Dendritic cells, such as the Langerhans cells of the skin and B lymphocytes that function to present antigens to Th cells, express class-II... 

Cells of the immune system other than Th cells that carry the CD4 are mono-cytes/macrophages, Langerhans, and dendritic cells. When HIV infects these cells, it follows a course typical of other retroviruses in which the infected cells... 

Lim HW, Hillsamer P, Kim CH Regulatory T cells can migrate to follicles upon T cell activation and suppress GC-Th cells and GC-Th cell-driven B cell responses. J Clin Invest 2004 114 1640-1649. 

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