Cytokines

• What are cytokines?

  Cytokines are small soluble proteins that regulate the immune system.
• What is the role of cytokines in the immune system?

  Cytokines orchestrate both innate immunity and the adaptive response to infection.
• What is pleiotropism in the context of cytokines?

  Pleiotropism refers to a single cytokine having different effects on various cells.
• What concentrations do cytokines act at?

  Cytokines act at picomolar to nanomolar concentrations.
• How do cytokines exert their effects on target cells?

  Cytokine action is mediated by binding to specific receptors on target cells.
• What are the three types of cytokine stimulation?

  • Autocrine Stimulation: affects the same cell that secreted it.
  • Paracrine Stimulation: affects a target cell in close proximity.
  • Endocrine Stimulation: the effect is systemic.
• What are the key features of cytokines?

  • Pleiotropism: a single cytokine can have different effects.
  • Redundancy: several different cytokines can have the same effect.
  • Act in networks.
  • Act as hematopoietic growth factors.
• What are interleukins?

  Interleukins are unrelated cytokines that meet specific criteria for classification.
• What are the criteria for a cytokine to be classified as an interleukin?

  They must have their genes cloned, be inducible in leukocytes, and have catalogued biological activities in inflammatory processes.
• What is the function of Interleukin 1 (IL-1)?

  IL-1 activates T helper cells, increases B cell numbers, and induces fever.
• What is the function of Interleukin 2 (IL-2)?

  IL-2 causes proliferation of activated T and B cells.
• What is the function of Interleukin 3 (IL-3)?

  IL-3 increases the number of mast cells in skin, spleen, and liver.
• What is the function of Interleukin 4 (IL-4)?

  IL-4 induces proliferation of T cells and class switching from IgM to IgG1 and IgE.
• What are some important cytokines and their cellular sources?

  • IL-1: Macrophages, B cells
  • IL-2: T cells
  • IL-3: T cells
  • IL-4: T cells
  • IL-5: T cells
  • IL-6: T cells, B cells
  • IL-7: Bone marrow stromal cells
  • IL-8: Monocytes
  • IL-9: T cells
  • IL-10: T cells
  • TNF: Macrophages, mast cells
  • IFN-α: Leukocytes
  • IFN-β: Fibroblasts
  • IFN-γ: T cells
• What are chemokines and their primary function?

  Chemokines are a family of cytokines that enhance motility and promote migration of white blood cells.
• What are the groups of chemokines and their names?

  • CC Chemokines: MCP-1, MCAF, JE, MIP-1α, MIP-1β, RANTES, Eotaxin
  • CXC Chemokines: GROα, MGSA, MIP-2, KC, IL-8, IP-10, CRG-2, SDF-1
• What is the primary role of interferons (IFN)?

  Interferons were named because they interfere with viral replication.
• What are cytotoxic/immunomodulatory/growth factors from the TNF family?

  They were first isolated from tumor cells and induce lysis in these cells.
• What are colony stimulating factors (CSF) and their sources?

  • CSFs are synthesized by bone marrow stromal cells, endothelial cells, fibroblasts, macrophages, and lymphocytes.
  • They control the proliferation and differentiation of committed hematopoietic cells.
• What are the five identified and isolated CSFs?

  • Granulocyte-Macrophage CSF (GM-CSF)
  • Granulocyte CSF (G-CSF)
  • Macrophage CSF (M-CSF)
  • IL-3
  • IL-7
• What are the cytokines associated with innate immunity and their actions?

  • IL-1β: Inflammation, fever, initiation of the acute-phase response
  • TNF-α: Inflammation, initiation of the acute-phase response, death of tumor cells
  • IL-6: Initiation of the acute-phase response, activation of B and T cells
  • TGF-β: Inhibition of T- and B-cell proliferation, induction of IgA
  • IFN-α and IFN-β: Protects cells against viruses, increases class I MHC expression
• What are the cytokines associated with adaptive immunity and their actions?

  • IL-2: Growth and proliferation of T and B cells, NK activation
  • IL-4: Promotion of Th2 differentiation, stimulation of B cells to switch to IgE production
  • IL-5: Eosinophil generation and activation, B-cell differentiation
  • IL-10: Suppression of Th2 cells, inhibition of antigen presentation
  • IFN-γ: Activation of macrophages, increased expression of class I and II MHC molecules
• What are cytokines?

  Small soluble proteins that regulate the immune system.
• How do cytokines function in the immune response?

  They orchestrate both innate immunity and the adaptive response to infection.
• Which cells usually secrete cytokines in response to an antigen?

  T cells.
• What is pleiotropism in the context of cytokines?


  A single cytokine can have different effects on various cells.
• What concentrations do cytokines typically act at?

  Picomolar to nanomolar concentrations.
• How is cytokine action mediated?

  By binding to specific receptors on target cells.
• What are the three types of cytokine stimulation?

  Autocrine, paracrine, and endocrine.
• What is autocrine stimulation?

  Affecting the same cell that secreted it.
• What is paracrine stimulation?

  Affecting a target cell in close proximity.
• What is endocrine stimulation?

  The effect is systemic and enters the circulation.
• What does pleiotropism mean in cytokine function?

  A single cytokine can have different effects on different cells.
• What is redundancy in cytokines?

  Several cytokines can have the same effects.
• How do cytokines act in networks?

  They interact with each other to regulate immune responses.
• What is a cytokine storm?

  A massive overproduction of cytokines leading to shock and multi-organ failure.
• Which cytokine is secreted by monocytes and macrophages and is involved in inflammation?

  Interleukin 1β (IL-1β).
• What is the role of Tumor necrosis factor-alpha (TNF-α)?


  It is involved in inflammation and the death of tumor cells.
• Which cytokine is produced by Th2 cells and activates B and T cells?

  Interleukin-6 (IL-6).
• What is the function of Transforming growth factor-beta (TGF-β)?

  It inhibits T and B cell proliferation and induces IgA.