Langerhans cells

Examples of Langerhans cells in the following topics:

• Types of Cells in the Pancreas

  • The islets of Langerhans are the regions of the pancreas that contain many hormone-producing endocrine cells.
  • The light-stained clusters of cells are called islets of Langerhans, which produce hormones that underlie the endocrine functions of the pancreas.
  • The islets of Langerhans can influence each other through paracrine and autocrine communication.
  • The hormone glucagon activates alpha cells which then activate beta cells and delta cells.
  • A porcine islet of Langerhans.

• Histology of the Pancreas

  • The pancreas serves digestive and endocrine functions, and it is composed of two types of tissue: islets of Langerhans and acini.
  • Lightly-staining clusters of cells are called islets of Langerhans.
  • The part of the pancreas with endocrine function is made up of approximately a million cell clusters called islets of Langerhans.
  • Four main cell types exist in the islets.
  • They are relatively difficult to distinguish using standard staining techniques, but they can be classified by their secretion: α cells secrete glucagon (increase glucose in blood), β cells secrete insulin (decrease glucose in blood), delta cells secrete somatostatin (regulates/stops α and β cells), and PP cells or gamma cells, secrete pancreatic polypeptide.

• Overview of Pancreatic Islets

  • Pancreatic islets, also called the islets of Langerhans, are regions of the pancreas that contain its hormone-producing endocrine cells.
  • The endocrine function of the pancreas helps maintain blood glucose levels, and the structures involved are known as the pancreatic islets, or the islets of Langerhans.
  • Insulin activates beta cells and inhibits alpha cells, while glucagon activates alpha cells, which activates beta cells and delta cells.
  • The islets of Langerhans are the regions of the pancreas that contain its endocrine (hormone-producing) cells.
  • The small cells in the middle are beta cells, and the surrounding larger cells are alpha, delta, gamma, and epsilon cells.

• Protection

  • The skin is composed of tough skin cells as well as a tough protein called keratin that guard tissues, organs, and structures underneath the skin against physical damage from minor cuts, scratches, and abrasions.
  • The skin also contains important cells called Langerhans cells. 
  • These cells help our immune system fight off infectious biological agents, like bacteria that try to get further into our body through skin that may have been compromised by physical damage. 

• Pancreas

  • The part of the pancreas with endocrine function is made up of approximately a million cell clusters called islets of Langerhans.
  • Four main cell types exist in the islets.
  • They are relatively difficult to distinguish using standard staining techniques, but they can be classified by their secretion: α cells secrete glucagon (increase glucose in blood), β cells secrete insulin (decrease glucose in blood), delta cells secrete somatostatin (regulates/stops α and β cells), and PP cells or gamma cells, secrete pancreatic polypeptide.
  • Nourse, the islets are "busily manufacturing their hormone and generally disregarding the pancreatic cells all around them, as though they were located in some completely different part of the body. " The islet of Langerhans plays an imperative role in glucose metabolism and regulation of blood glucose concentration.
  • In humans, the secretory activity of the pancreas is regulated directly via the effect of hormones in the blood on the islets of Langerhans and indirectly through the effect of the autonomic nervous system on the blood flow.

• Structure of the Skin: Epidermis

  • The newly produced cells push older cells into the upper layers of the epidermis with time. 
  • From the stratum basale, the keratinocytes move into the stratum spinosum, a layer so called because its cells are spiny-shaped cells. 
  • They are dead skin cells filled with the tough protein keratin. 
  • The epidermis is made up of 95% keratinocytes but also contains melanocytes, Langerhans cells, Merkel cells, and inflammatory cells.
  • The stratum basale is primarily made up of basal keratinocyte cells, which can be considered the stem cells of the epidermis.

• Interactions of Hormones at Target Cells

  • For example, thyroid hormones increase the number of receptors available for epinephrine at the latter's target cell, thereby increasing epinephrine's effect at that cell.
  • Bundles of cells in the pancreas, called the islets of Langerhans, contain two kinds of cells: alpha cells and beta cells.
  • Beta cells secrete insulin.
  • Liver and muscle cells convert glucose to glycogen, for short-term storage, and adipose cells convert glucose to fat.
  • Alpha cells secrete glucagon.

• Specific T-Cell Roles

  • T helper cells assist the maturation of B cells and memory B cells while activating cytotoxic T cells and macrophages.
  • Differentiation into helper T cell subtypes occurs during clonal selection following T cell activation of naive T cells.
  • Cytotoxic T cells (TC cells, or CTLs) destroy virally infected cells and tumor cells, and are also cause much of the damage in in transplant rejection and autoimmune diseases.
  • Memory T cells comprise two subtypes: central memory T cells (TCM cells) and effector memory T cells (TEM cells), which have different properties and release different cytokines.
  • Regulatory T cells (Treg cells), also known as suppressor T cells, are crucial for the maintenance of immunological tolerance.

• Natural Killer Cells

  • The role of NK cells is similar to that of cytotoxic T cells in the adaptive immune response.
  • NK cells provide rapid responses to virus-infected cells and respond to tumor formation by destroying abnormal and infected cells.
  • NK cells use wo cytolytic granule-mediated apoptosis to destroy abnormal and infected cells.
  • Virus-infected cells destroyed by cell lysis release their replicated virus particles into the body, which infects other cells.
  • Cells that are osponized with antibodies are easier for NK cells to detect and destroy.

• Lymphoid Cells

  • The three major types of lymphocyte are T cells, B cells, and natural killer cells.
  • If cancer cells evade NK cell detection for long enough, however, they can grow into tumors that are more resistant to NK cell activity.
  • T cells are involved in cell-mediated immunity whereas B cells are primarily responsible for humoral immunity.
  • There are two types of T cells involved in adaptive, cell-mediated immunity.
  • Following activation, B cells and T cells leave a lasting legacy of the antigens they have encountered in the form of memory cells.