Dendritic cells?

Question

Hey, anyone know anything about the role of dendritic cells in the activation and regulation of immunity?
Xx~xX

Answer 1

Dendritic cells (DC) main function is to process antigen material and present it on their surface to other cells of the immune system. Once activated, they migrate to the lymphoid tissues where they interact with T cells and B cells to initiate and shape the immune response.

Answer 2

Hi there,

You've had loads of information about activation of immunity by dendritic cells presenting antigen to T cells in order to provoke an immune response but I haven't seen much about regulation. There is a suggestion that dendritic cells are involved in regulation of immune responses in the gut, although this is only theory and not necessarily fact. The gut is exposed to a wide range of antigens, both harmful (e.g. pathogenic bacteria) and harmless (e.g. food). The gut immune system needs to distinguish between the two different types and respond to them accordingly. If you start to mount an immune response to food then this would be damaging and you would end up with chronic diarroheoa, however, if you ignored pathogenic bacteria then you would also get sick so you need to be able to tell the difference. In general, we don't make immune responses to food antigens, this is known as "oral tolerance". There are 2 time points when oral tolerance can be generated.

1) The activator stage: this is when dendritic cells migrate to the lymph node (or Peyer's patch in the gut) and present antigen to T cells. At this point the dendritic cells could provide tolerising signals to the T cells and prevent an immune response.

2) The effector stage: the T cells in the gut don't respond to their cognate antigen, they are either deleted, simply ignore the antigen (anergy) or are regulated by T regulatory cells.

Although the mechanism is still unclear, it is possible that dendritic cells play a role in regulating the immune response to harmless antigens in the gut. It also appears that dendritic cells are able to undergo transient interactions with T cells in the lamina propria of the gut, whether this is to activate or regulate them is unclear. As with a lot of science, we still have a lot to learn but I think you've got most of the story so far. Hope this helps.

Answer 3

Dendritic cells can be thought of as the connective components of the innate and the adaptive immune system. When a pathogen invades the body, macrophages are activated and they send out signals, cytokines, which are picked up by neutrophils and dendritic cells. Neutrophils extravasate blood vessels and engulf and destroy the pathogen. When extra help is needed, Dendritic cells also engulf pathogens and antigens, molecules from the pathogen that are recognised by the immune system cells, are produced. Dendritic cells display these antigens on their surface by loading them onto the Major Histocompatibility Complex (MHC) molecules. MHC class I molecules are used for antigen presentation if the invader is a virus and if it is a bacterium, MHC class II molecules are used. Then the Dendritic cells migrate to the lymphatic system. This part of the immune response marks the adaptive immune response. In the lymphatic system, the Dendritic cells present the antigens to T-cells and activate them. Subsequent cellular amd humoural communications lead to the production of antibodies which bind to pathogenic antigens and form aggregates that can be taken up by T-cells. Cytotoxic T-cells, CTLs, also directly kill pathogen by binding and inducing apoptosis.

Dendritic cells are the main connections between these pathways. Some viruses such as HIV-1 infect primarily follicular dendritic cells among other cell types such as T-cells and macrophages.

Answer 4

There are different types of cell in the immune system, including T-cells, B-cells and dendritic cells. T-cells and B-cells produce substances such as cytokines and antibodies when they have been activated. The dendritic cells are responsible for activating these cells. By presenting foreign particles (from viruses, bacteria etc) on the surface of their cell membranes they interact with receptors on T and B cells which cause activation.

They are involved in immunity because repeated activation of these cells will produce memory cells which will remain in your body for years. The presence of memory cells means your body is able to react to and kill this foregin material quickly if it sees it again without any symptoms of infection.

Answer 5

they process antigen material (main proteins, membrane proteins etc) and display this information on the cell membrane to be seen from T-cells that will become activated and start looking for this antigens to destroy
this is just an over symplified version you should actually check a biology book (alberts et al 4th ed.)

Answer 6

Dendritic cells (DC) play a key role in the immunological reactions throughout the body. Dendritic cells (DC) and their immature counterparts, Langerhans cells (LC), are highly specialized antigen-presenting cells (APC) located in the skin, mucosa, and lymphoid tissues. DC and LC play a key role in the induction phase of contact allergenicity, and it is likely that these cells can be used to develop in vitro assays for contact sensitization and other immunological reactions of the body.

Dendritic cells (DCs) are potent antigen presenting cells (APCs) that possess the ability to stimulate naïve T cells. They comprise a system of leukocytes widely distributed in all tissues, especially in those that provide an environmental interface. DCs posses a heterogeneous haemopoietic lineage, in that subsets from different tissues have been shown to posses a differential morphology, phenotype and function. The ability to stimulate naïve T cell proliferation appears to be shared between these various DC subsets. It has been suggested that the so-called myeloid and lymphoid-derived subsets of DCs perform specific stimulatory or tolerogenic function, respectively. DCs are derived from bone marrow progenitors and circulate in the blood as immature precursors prior to migration into peripheral tissues. Within different tissues, DCs differentiate and become active in the taking up and processing of antigens (Ags), and their subsequent presentation on the cell surface linked to major histocompatibility (MHC) molecules. Upon appropriate stimulation, DCs undergo further maturation and migrate to secondary lymphoid tissues where they present Ag to T cells and induce an immune response. DCs are receiving increasing scientific and clinical interest due to their key role in anti-cancer host responses and potential use as biological adjuvants in tumour vaccines, as well as their involvement in the immunobiology of tolerance and autoimmunity.

Dendritic cells (DCs), originally identified by Steinman and his colleagues (1972) represent the pacemakers of the immune response.1 They are crucial to the presentation of peptides and proteins to T and B lymphocytes and are widely recognized as the key antigen presenting cells (APCs). They are critical for the induction of T cell responses resulting in cell-mediated immunity (CMI). The T cell receptors (TCRs) on T lymphocytes recognize fragments of antigens (Ags) bound to molecules of the major histocompatibility complex (MHC) on the surfaces of APCs. The peptide binding proteins are of two types, MHC class I and II, which interact with and stimulate cytotoxic T lymphocytes (CTLs) and T helper cells (Ths), respectively. On entry into APCs, Ags are processed, spliced into peptides in the cytosol and then reexpressed on the cell surface linked to MHC proteins. When bound to MHC class I molecules, CTLs are generated and activated and cells in tissues expressing the Ags (e.g. virus infected cells, cancer cells) are recognised and destroyed. Antigens reexpressed on the cell surface linked to MHC class II molecules interact with Th cells which when activated have profound immune-regulatory effects.2 Thus, DCs play a key role in host defenses and a crucial role in putative anti-cancer immune responses.

Bucket loads more info at the link.

Answer 7

These may help you

http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6VRT-4DVM8BN-G&_coverDate=11%2F23%2F2004&_alid=507398134&_rdoc=1&_fmt=&_orig=search&_qd=1&_cdi=6243&_sort=d&view=c&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=8a5397e0a902472d37179d43e5724102

I know long link but it works.

http://www.bloodjournal.org/cgi/content/abstract/104/8/2235

These arearticles that you can download.
Look for the .pdf file link on the right side.

http://www.immunity.com/content/article/abstract?uid=PII1074761395901752

http://www.cell.com/content/article/abstract?uid=PII0092867494904189&session=

http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6WSN-418PXGB-2&_coverDate=10%2F31%2F1997&_alid=507400570&_rdoc=1&_fmt=&_orig=search&_qd=1&_cdi=7051&_sort=d&view=c&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=712b3bc2c0d7989b8f953f0d2bb213fe

http://www.immunity.com/content/article/abstract?uid=PII1074761395901752