During specific immunity, competent T (CD4+) cells are activated by?
146838
First, the interaction between an APC and a halper T cell is greatly enhanced by the presense of a T cell surface protein called CD4. Present on most helper T cells, CD4 binds to part of the class II MHC proteins. The interactions between CD4 and Class II MHC proteins molecules helps keep the helper T cell and the APC joined while activition of the Th cell occurs. IT is thus activitated by Class II MHC Molecules. Class II MHC are macrophages, B cells and activated T Cells. THese are essentially antibodies. that final part i am not sure. It is true by the transitive property.
845531
T cells are  lymphocytes that mature in the thymus (hence T).They form an important part of your 'adaptive' immune system transported in the blood, along with other cells. T cells have special antigen receptors on their surfaces and can bind to a specific shape, then multiply themselves so they form an 'army' of specialised fighting cells.  They fight things such as pathogenic bacteria as well as viruses, parasites, fungal spores and all manner of things that could make you ill.  \n\nThere are different types of T cells that work in different ways e.g. cytotoxic T cells and Helper T cells which are specialised to fight infection etc.  With repeated infections, they become more efficient producing various substances that can e.g. kill viruses.  They work in conjunction with the B cells, another type of lymphocyte which produce antibodies to the marauding bacteria etc.\n\nSo without T cells, you would be left with generalised  or innate immunity (non-adaptive) which would help fight infection to some extent (e.g. by phagocytosis i.e. gobbling up bacteria etc), but would not 'remember' infections next time around like the more effective 'adaptive' immune system.
223927
ANTIBODIES,T C CELLS,T H CELLS,PHAGOCYTOSIS,MHC,CD,COMPLEMENT SYSTEM,APP,CRP,INTERLEUKIN\n,INTERFERON,\nMACROPHAGES,\nNK CELLS,\nCATHELICIDIN,HYPERSENSITIVITY....10 DONE...\nTHERE IS MUCH MORE....BODY IS A BIG TIME FIGHTER...\nINFECTIONS DONOT MESS  WITH IT
82949
To trigger a biological response.
305237
Innate immunity - non-specific to a particular pathogen, macrophages important cells here.  Also involves inflammation and acute phase response\n\nAdaptive immunity - specific and has 'memory cells'. Involves humoral immunity and cell mediated responses.  Involves reactions to specific antigenic challenges.\n\nComparative immunity - signal transduction pathways used to invoke immunity that are similar across a wide range of organisms - vertebrates, insects and even plants!!!  Don't really know much about this found it in a book, see source below!!!
1173349
CD4 is an immune marker.\nit is the binding site that the HIV virion attach to on the surface of the t-cell.  you could say CD4 is the DOOR LOCK and HIV its the KEY....  once the key fits into place.... well... your part of the club.
1082845
Perhaps it's because the fungus is usually attached to or inside macrophages.  Without a proper T-cell response, you don't get activation of your monocyte derived cells, so you don't as strong of a proliferation compared to a person with a functioning immune system.  Complete shot in the dark.\n\nUpdate:  I just realized that HIV also attacks macrophages because they also contain CD4.  So, no macrophages equals no infection with blastomycosis.
1170491
17AAG - http://www.newscientist.com/channel/health/cancer/mg18625053.700\n\n Peripheral Blood Mononuclear Cell (PBMC) is a blood cell having a round nucleus, such as a lymphocyte or a monocyte. These blood cells are a critical component in the human immune system to fight infection and adapt to intruders
387461
Well, I dont know if your are looking for a simple answer or extensive article. But i will try to sum it up in a simple fashion.\n\nTwo type of lymphocytes\n\nCD 4 (Helper T cell)\n\nCD 8 (Cytotoxic T cell)\n\n\nCD 8:\nis responsible for protection against and fighting :\nEndogenous Peptides e.g.\nViruses\nIntracellular Bacteria ( thankfully there are not many)\nIntracellular Parasites\nNeoantigens (tumor cells)\nGraft\n\nCD 4:\nis responsible for protection against and fighting:\nExogenous Peptides e.g\nBacteria ( which are neumerous day to day infections and            \n          varied from staphylococuss to anthrax and more; \n          like day to day cold to plaque)\nToxins\n\nHIV hampers the function of these cells and as this branch of immumity gets weaker, other branches are affected to and the individual is severly immunocompromised.
400670
Innate immunity: defence mechanisms that are non-specific and ubiquitous. Think of it as the cannon fodder of the human immune system. These are the cells that are often first on the scene, and charge in blindly, attacking everything left, right and center, and then die. Kind of like suicide bombers. Only good.\n  Includes cells such as neutrophils, monocytes, macrophages, dendritic cells, and very importantly, the entire complement system.\n\n------\n\nAquired immunity: also called adaptive immunity, comes from exposure to immunogens.\n  Includes B cells and T cells. B cells make antibodies after being exposed to an immunogen. Encountering that foregin body again (now called an "antigen") will cause the adaptive immune system to react faster than it did previous (because it has this antibody memory, now. Thats why its adaptive, or aquired).
574003
In human anatomy, the thymus is an organ located in the upper anterior portion of the chest cavity. The thymus plays an important role in the development of the immune system in early life, and its cells form a part of the body's normal immune system. It is most active before puberty, after which it shrinks in size and activity in most individuals and is replaced with fat.\n\nThe thymus is also present in many other animals. When animal thymus tissue is sold in a butcher shop or at a meat counter, thymus is known as sweetbread.\n\n\nFunction:\nThe function of the thymus in the immune system was determined by Jacques Miller. In the two thymic lobes, lymphocytes precursors mature into T cells (where T stands for “thymus”)[1]. The key function of the thymus is the selection of the T cell repertoire that the immune system uses to combat infections. This involves selection of T cells that are functional (positive selection), and elimination of T cells that are autoreactive (negative selection). Positively-selected cells will be taken care of by specialized Nurse Cells. In order to be positively-selected, pre-T cells will have to interact with several cell surface molecules, MHC/HLA, to ensure reactivity and specificity. Cells that pass both levels of selection are released into the bloodstream to perform vital immune functions. Negative selection is not 100% complete. Some autoreactive T cells escape thymic censorship, and are released into the circulation. Additional mechanisms of tolerance active in the peripheral exist to silence these cells such as anergy, deletion, cross-tolerance and regulatory T cells. If these mechanisms also fail, autoimmunity may arise.\n\nFurther info: \n\nhttp://en.wikipedia.org/wiki/Thymus
256430
HLA are Human Leukocyte Antigens.  HLAs are products of your Major Histocompatibility Complex I (MHC I) genes. HLAs couple with the products of antigen digestion in the cell (peptide fragments of viruses for example) and are required components for the process of antigen presentation to T and B lymphocytes.  T and B  lymphocytes are then 'activated' by the antigen presentation.  So... HLAs participate in antigen presentation to activate T and B lymphocytes.
474181
The structural interaction between the human T-cell receptor (TCR), and the antigenic peptide as linked to a major histocompatibility complex (MHC) molecule are fundamental to the workings of the immune system. Previous work has shown that when a virus or bacteria invades the body, the immune system first breaks up cells infected by the invaders. These infected cells are 'flagged" with a combination of the foreign protein and an MHC molecule and bound to a TCR. Roving T-cells then recognize and destroy these flagged cells. \n\nBut until now, no one has known what the atomic structure of this immune interaction looked like. Harvard researchers, led by Don C. Wiley of the Department of Molecular and Cellular Biology, determined that TCR structure resembles that of another key component of the immune system, antibodies, particularly, the anitgen-binding region. This discovery led the way to the identification of the entire structure of the MHC-TCR complex. \n\nThe research indicates that the antigenic peptide produced by degradation of the invading virus within the cell is held within the MHC binding cleft almost like a hot-dog is held in a bun. This peptide and most of the MHC molecule are engulfed by the TCR. \n\nIn a related study, researchers at the University of Maryland Biotechnology Institute gained new insight into the phenomenon of superantigen creation. In some cases, the TCR-MHC interaction leads to an overreaction by T-cells. This overactive immune creates superantigens have that have been implicated in diseases and complications as varied as toxic shock syndrome, diabetes mellitus and multiple sclerosis. \n\nThe researchers showed for the first time how a superantigen protein (in this case, the peptide toxin produced by the bacterium Staphylococcus aureus) binds to the TCR. The work showed that by bringing the MHC and TCR together directly, regardless of the peptide bound to the MHC, the superantigen circumvents the normal mechanism for T-cell activation by specific peptide-MHC complexes, and triggers a more general reaction instead. \n\nThe basis for the current work can be traced back to 1974, when Drs. Rolf Zinkernagel and Peter Doherty determined that killer T-cells sense infected target cells by the identification of viral antigens displayed on the cell surface in combination with MHC proteins. This process has become known as MHC restriction. The two scientists shared the Nobel prize this year for this work.
52588
B CELLS ARE ANTI-BODY PRODUCERS AND THEIR ORIGIN IS RED MARROW.\nT CELLS DO NOT PRODUCE ANTIBODIES SOME ARE KILLERS,SOME ARE HELPERS, SOME UNDERGO PHAGOCYTOSIS ALL BECOME COMPOTENT IN LYMPHATIC TISSUE AND ESPECIALLY IN THE YOUNG THYMUS GALND AFTER A RED MARROW ORIGIN.
144376
The immune system is composed of many interdependent cell types that collectively protect the body from bacterial, parasitic, fungal, viral infections and from the growth of tumor cells. Many of these cell types have specialized functions. The cells of the immune system can engulf bacteria, kill parasites or tumor cells, or kill viral-infected cells. Often, these cells depend on the T helper subset for activation signals in the form of secretions formally known as cytokines, lymphokines, or more specifically interleukins. The purpose of this article is to review the organs, cell types and interactions between cells of the immune system as a commentary on their importance and interdependence on the T helper subset. Such an understanding may help comprehend the root of immune deficiencies, and perceive potential avenues that the immune system can be modulated in the case of specific diseases.
126833
It means they have the Cluster of Differentiation (CD) 4 antigen on their surface. They are a white cell line, the ones that protect your body from infection. The CD4 receptor is involved in HIV infection.
576814
The cell-mediated response involves cells that are specific to the antigens on the invading pathogens. These cells are called T cells. The T-cells develop surface receptors called T-cell receptors where they become programmed for the antigen of a specific pathogen.  Some of the T cells recognize and destroy foreign cells.  Hope this helps. I just had an exam on it and passed!!