What Is the Langerhans Cell?
Langerhans cells (also known as Langerhans cells) are dendritic cells (antigen-presenting cells) in the skin and mucous membranes. They contain organelles called Birbaker particles, and Langerhans are present in any layer of the epithelium. Cell. Langerhans cells (LC) are derived from bone marrow and spleen, and later migrate into the skin, mainly distributed in the upper and middle epidermis. Between epidermal spinal cells, they can also be found in the dermis, oral mucosa, esophagus, lymph nodes, thymus, and spleen. Office. It has dendritic protrusions that extend between the keratinocytes adjacent to the epidermis, from the upper layer to the granular layer, and from the lower part to the junction of the epidermis and dermis.
Basic Information
- Chinese name
- Langerhans cell
- Foreign name
- Langerhans cell
- Morphological characteristics
- Keratin-free and melanosomes
- Langerhans cell is an immune-active cell derived from bone marrow. It is an antigen-presenting cell with special immune stimulating ability. It has a strong recognition consciousness, functions of uptake and presentation of foreign antigens, and is used in the human defense system. Plays an extremely important role [1]
- Under electron microscope, Langerhans cells do not contain keratin filaments and melanosomes, and do not have a desmosome structure. The most important feature is the characteristic Birbeck particles (also known as Langerhans particles) in the cytoplasm. Cells present structural features of metabolically active cells, such as the nucleus being lobulated or curved, with more mitochondria, developed Golgi complexes, endoplasmic reticulum, and lysosomes. Cells have phagocytosis, but their ability to phagocytose is weaker than macrophages.
Observed under conditions of about 2000 times, it is transparent because there is no keratin filaments in the cytoplasm. It is as easy to find as melanocytes, but Langerhans cells are located between the spinous cells in the upper and middle epidermis. Observing under conditions of more than 20 000 times can find Birbeck particles. Birbeck particles are mostly located in the cytoplasm near the depression of the nucleus. They are about 150 to 300 nm long and 40 nm wide. There are prominent spherical bubbles, showing a tennis racket-like structure. At present, Birbeck granules are considered to be a cytoplasmic membrane invaginated when Langerhans cells engulf foreign antigens, and are a form of phagosome or antigen storage for digesting extracellular substances.
- The surface marks of Langerhans cells are quite similar to macrophages. Therefore, Langerhans cells are antigen-presenting cells of the skin. They can recognize, bind, and process antigens that invade the skin, and transmit the antigens to T cells. They are skin immunity. Functionally important cells. It plays an important role in contact allergy, antiviral infection, rejection of allograft tissue and immune surveillance of epidermal cancerous cells. Such cells have been shown to play an important role in delayed skin hypersensitivity. Some people think that it is related to the metabolism of hormones, which can activate sterols and turn them into vitamin D substances.
Langerhans cells are not permanently fixed in the epidermis, but are constantly renewed. The Langerhans cells carrying the antigen entered the lymphatic vessels and turned into veil cells. The latter entered the thymus-dependent region of local lymph nodes and became staggered cells. [3]