Dendritic cells
Dendritic cells are antigen-presenting cells and they serve as a connection between specific immunity and non-specific immunity. Dendritic cells, just as all other cells of immune system, originate from hematopoietic stem cell, and they are capable of phagocytosis.
In our organism, dendritic cells exist in two forms, mature and immature.
Immature dendritic cells[edit | edit source]
Immature dendritic cells are present in tissues which are in the direct contact with external environment, such as skin (dendritic cells present in the skin are called the Langerhans cells), nasal mucosa, oral mucosa, lungs, intestine or stomach. They are using their protrusions to capture foreign molecules and to search for new possible pathogens (for this purpose, they use toll-like receptors and pattern recognition receptors). Dendritic cells are also traveling between blood and lymph, and patrolling in almost every organ of human body, except the brain, testicles and cornea. The function of immature dendritic cells is to absorb the body's own dead cells, and molecules dissolved in the intercellular fluid. Their fragments are then exposed on the surface of dendritic cell in complex with MHC (Major Histocompatibility Complex) as autoantigens, which are recognized by specific T cells. In this way, T cells are inhibited or they become regulatory T cells. Thanks to this mechanism, immature dendritic cells are inducing a tolerance towards body's own antigens.
If the immature dendritic cell recognizes a pathogen, or a body's own cell which has died by a necrosis, it becomes mature.
Mature dendritic cells[edit | edit source]
Mature dendritic cells present the fragments of exogenous pathogen in a complex with MHC II molecule. Endogenous antigens (including viruses) are presented together with MHC I. Mature dendritic cell looses the ability of phagocytosis and travels to the secondary lymphatic organs, where it serves as an activator of T lymphocytes. In this way, mature dendritic cells contribute to the activation of specific immunity. Mature dendritic cells only live for 2-3 days approximately, and they are being continuously supplemented from the bone marrow.
Clinical use of dendritic cells[edit | edit source]
Nowadays, new researches and studies are trying to use dendritic cells in the induction of anti tumor imunity. Monocytes which were in vitro taken from the patients body, are used in the creation of dendritic cells. A specific tumor antigen is then added to these dendritic cells, and after the fragments being processed and exposed at the surface, cells are implemented back to the patients body. It is possible that dendritic cells may also contribute to the cure of allergy or HIV.
Links[edit | edit source]
Related articles[edit | edit source]
- Antigen-presenting cells
- Phagocytosis
- Major Histocompatibility Complex
- Non-specific immunity
- Specific immunity
- T cells
Used literature[edit | edit source]
- ŠTERZL, Ivan, et al. Základy imunologie pro zubní a všeobecné lékaře. 1. edition. Prague: Karolinum, 2005. 207 s. ISBN 978-80-2460-972-0.
- HOŘEJŠÍ, Václav a Jana BARTŮŇKOVÁ. Základy imunologie. 4. edition. Prague: Triton, 2009. 320 s. ISBN 978-80-7387-280-9.
- What are Dendritic Cells? [online]. [cit. 2015-10-23]. Available from: https://www.news-medical.net/health/what-are-dendritic-cells.aspx
Category: Immunology Category: Physiology
