Effector cells

A mechanism of cell-mediated immunity whereby an effector cell of the immune system actively lyses a target cell that has been bound by specific antibodies. The typical ADCC involves activation of natural killer (NR) cells and is dependent on the recognition of... 

Antigen-presenting cells (APCs) are cells of the immune system that are able to process and present foreign antigens to effector cells. The antigen is presented in the context of an MHC-I or MHC-II molecule on APCs in the presence of so-called costimulatory molecules to activate the effector cells. 

Bronchial Asthma. Figure 2 Mechanisms of bronchial hyperresponsiveness. Toxic products from eosinophils [cationic peptides, reactive oxygen species (ROS)] cause epithelial injury. Nerve endings become easily accessible to mediators from mast cells, eosinophils [eosinophil-derived neurotoxin (EDN)], and neutrophils, and to airborne toxicants such as S02. Activation of nerve endings stimulates effector cells like mucosal glands and airway smooth muscle either directly or by cholinergic reflexes. 

Parallel to orchestrating acute inflammatory processes by providing an optimal milieu of cytokines, mediators, and adhesion molecules in order to recruit and activate effector cells to the site of infection, dendritic cells also setve as professional antigen-presenting cells for cells of the adaptive immune system ( antigen presentation ... 

In the specialized environment of secondary lymphoid tissues such as lymph nodes or spleen, dendritic cells provide the requirements for naive T-lymphocytes to become activated and to proliferate. The professional antigen-presenting cells present peptides in MHC II, express costimulatory molecules, and release cytokines into the immunological synapse, which is formed by the antigen-presenting cell and the naive T-lymphocyte. Thus, cells of innate immunity initiate and facilitate the activation of naive lymphocytes, and it is easily conceivable that their cytokines and adhesion molecules will instruct the naive T-lymphocyte during activation and differentiation to T-effector cells. 

TLRs and is highly active in pDC which are robust producers of IFN-a and represent crucial effector cells of the innate defense system. 

The key end result of TLR signalling is the induction of cytokines. Cytokines are proteins produced during an immune response that allow the maturation, activation and differentiation of effector cells in the immune system. The activation of NFkB and AP-1 by the MyD88 and the TREF dependent pathways leads to the production of proinflammatory cytokines such as IL-6, TNF-a and various chemokines. This pathway can also activate IRF-7 via TLR-7and TLR-9 allowing Type-I interferons to be produced. 

The PNS has two neurohormones (neurotransmitters) acetylcholine (ACh) and acetylcholinesterase (ACliE). ACh is a neurotransmitter responsible for die transmission of nerve impulses to effector cells of die parasympathetic nervous system. ACh plays an important role in die transmission of nerve impulses at synapses and myoneural junctions. ACh is quickly... 

It is generally accepted (based on clinical and in vitro studies) that mast cells (and basophils), IgE and FceRI are involved in most cases of allergen-induced anaphylaxis in humans. However, it is difficult to define the exact roles and relative importance of mast cells, basophils, and other potential effector cells (e.g monocytes/macrophages, dendritic cells) in either IgE-dependent or IgE-independent human anaphylaxis. Unlike in mice, we neither have access to mast cell- or basophil-deficient humans nor can we genetically manipulate human subjects to produce such phenotypes. 

The roles of potential effector cells other than mast cells and basophils (e.g. monocytes/ macrophages, dendritic cells) in IgE-dependent and IgE-independent anaphylaxis in mice and humans remain to be determined. 

There may be substantial variation both within and among species (e.g., in mice vs. humans) in the expression of various proteins, receptors and/or ligands that influence the activation of mast cells (or basophils or other potential effector cell types), or that can regulate the responsiveness of end organ target cells (e.g., bronchial or gastrointestinal smooth muscle cells, vascular endothelial cells) to potential mediators of anaphylaxis derived from mast cells. 

Roy S, Cain KJ, Chapin RB, Charboneau RG, Barke RA (1998) Morphine modulates NF kappa B activation in macrophages. Biochem Biophys Res Commun 245 392-396 Roy S, Wang J, Gupta S, Charboneau R, Loh HH, Barke RA (2004) Chronic morphine treatment differentiates T helper cells to Th2 effector cells by modulating transcription factors GATA 3 and T-bet. J Neuroimmunol 147 78-81... 

Immunological tests were performed for studying the reactive of peritoneal-exudative cells, especially peritonial macrophages, which are the main effector cells involved in natural resistance (host defence system) against bacterial infection. 

The selective stimulation of these cells is of importance because they are the most active effector cells in host defense mechanisms against bacterial and viral infections. 

EPA Eicosapentaenoic acid EpDIF Epithelial-derived inhibitory factor also known as epithelium/derived relaxant fector EPO Eosinophil peroxidase EPOR Erythropoietin receptor EPR Effector cell protease EPX Eosinophil protein X ER Endoplasmic reticulum ERCP Endoscopic retrograde cholangiopancreatography E-selectin Endothelial selectin formerly known as endothelial leucocyte adhesion molecule-1 (ELAM-1)... 

Type I reactions occur when the drug or its bound hapten incites an IgE antibody response. IgE binds to high-affinity receptors on mast cells and basophils. When the original antigen cross-links the cell-bound IgE, the effector cell releases enormous amounts of preformed mediators, producing the... 

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. 

A delicate balance between host and donor effector cells is necessary, and residual host-versus-graft effects may lead to graft failure, which is also known as graft rejection. Graft failure is defined as the lack of functional hematopoiesis after HCT and can occur early (i.e., lack of initial hematopoietic... 

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