cytokines

Examples of cytokines in the following topics:

• Cytokine Therapy

  • They are a diverse array of recombinant, synthetic, and natural preparations, often cytokines.
  • Cytokines are characterized by considerable "redundancy", in that many cytokines appear to share similar functions.
  • It seems to be a paradox that cytokines binding to antibodies have a stronger immune effect than the cytokine alone.
  • In recent years, the cytokine receptors have come to demand the attention of more investigators than cytokines themselves, partly because of their remarkable characteristics, and partly because a deficiency of cytokine receptors has now been directly linked to certain debilitating immunodeficiency states.
  • Oversecretion of cytokines can trigger a dangerous syndrome known as a cytokine storm.

• Growth Factors

  • Growth factors, cytokines, and hormones are all chemical messengers that mediate intercellular communication.
  • Growth factors are typically cytokines or hormones, but not all cytokines and hormones are growth factors.
  • A cytokine is a small protein involved in cell signaling.
  • Confusingly, cytokine and growth factor are sometimes used as interchangeable terms.
  • A cytokine differs from a hormone in that it is not secreted from a gland.

• Cytokines and Chemokines

  • Cytokines and chemokines are both small proteins secreted by cells of the immune system.
  • Cytokines can be classified as proteins, peptides, or glycoproteins.
  • As of 2008, the current terminology refers to cytokines as immunomodulating agents.
  • These are a family of small cytokines, or proteins secreted by cells.
  • However, these proteins have historically been known under several other names including the SIS family of cytokines, SIG family of cytokines, SCY family of cytokines, Platelet factor-4 superfamily or intercrines.

• Types of Cytokines Participating in Immune Response

  • Cytokines can be classified as proteins, peptides, or glycoproteins.
  • Each cytokine has a matching cell-surface receptor.
  • Interleukins are a class of cytokines primarily expressed by leukocytes.
  • Interferons are protein cytokines that have antiviral functions.
  • By definition, inflammatory mediators in other classes of cytokines are also considered chemokines.

• Pathogen Recognition

  • One subclass of cytokines is the interleukin (IL), which mediates interactions between leukocytes (white blood cells).
  • In addition to being released from cells after PAMP recognition, cytokines are released by the infected cells which bind to nearby uninfected cells, inducing those cells to release cytokines, resulting in a cytokine burst.
  • A second class of cytokines is interferons , which are released by infected cells as a warning to nearby uninfected cells.
  • Interferons are cytokines that are released by a cell infected with a virus.
  • Describe the role of PAMPs and PRRs, interferons, and other cytokines in innate immunity

• Natural Killer Cells

  • These cells named "natural killers" because they were thought to work without cytokine or chemokine activation.
  • Cytokines play a role in NK cell activation.
  • Many cells release cytokines as a result of cellular stress when infected with a virus.
  • Cytokines involved in NK activation include IL-12, IL-15, IL-18, IL-2, and CCL5.
  • NK cells are activated in response to interferons or macrophage-derived cytokines.

• Type IV (Delayed Cell-Mediated) Reactions

  • Cell-mediated immunity is an immune response that does not involve antibodies, but rather involves the activation of phagocytes, natural killer cells (NK), antigen-specific cytotoxic T-lymphocytes, and the release of various cytokines in response to an antigen.
  • Cytotoxic T cells cause death by apoptosis without using cytokines.
  • Therefore in cell mediated immunity cytokines are not always present.
  • 3. stimulating cells to secrete a variety of cytokines that influence the function of other cells involved in adaptive immune responses and innate immune responses
  • CD4+ T cells secrete IL-2 and interferon gamma, further inducing the release of other Th1 cytokines, thus mediating the immune response.

• Superantigens

  • Superantigens are a class of antigens that cause activation of T-cells and massive cytokine release.
  • More importantly, the large number of activated T-cells secretes large amounts of cytokines, the most important of which is Interferon gamma.

• Phagocyte Migration and Phagocytosis

  • In the tissues, they are activated by cytokines and arrive at the battle scene ready to kill.
  • These chemical signals may include proteins from invading bacteria, clotting system peptides, complement products, and cytokines that have been given off by macrophages located in the tissue near the infection site.
  • Another group of chemical attractants are cytokines that recruit neutrophils and monocytes from the blood.
  • Chemotaxis is the process by which phagocytes follow the cytokine "scent" to the infected spot.

• Specific T-Cell Roles

  • Helper T cells assist other white blood cells in immunologic processes by facilitating cytokines that activate and direct other immune cells.
  • Once activated, they divide rapidly and secrete regulatory cytokines such as IFN-gamma and certain interleukins.
  • These cells can differentiate into one of several subtypes, including TH1, TH2, TH3, TH17, or TFH, which secrete different cytokines to facilitate a different type of immune response.
  • 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.
  • Once activated, these cells perform functions ascribed to both Th and Tc cells (i.e., cytokine production and release of cytolytic/cell killing molecules).