Cytokines

• What are cytokines?

  Small secreted proteins regulating immunity
• What do cytokines mediate and regulate?

  Immunity, inflammation, and hematopoiesis
• What type of molecules can cytokines be?

  Proteins or glycoproteins
• Who secretes cytokines?

  White blood cells and various other cells
• What triggers the secretion of cytokines?

  A number of stimuli

  
• What are the roles of cytokines in the body?

  • Development of immune responses
  • Induction of inflammatory response
  • Regulation of hematopoiesis
  • Control of cellular proliferation and differentiation
  • Healing of wounds

  
• How do cytokines exert their effects on target cells?

  By binding to specific receptors on membranes

  
• What is the affinity of cytokines for their receptors?

  Very high affinity at picomolar concentrations
• What is autocrine action of cytokines?

  Binding to receptors on the same cell that secreted it

  
• What is paracrine action of cytokines?

  Binding to receptors on nearby target cells

  
• What is endocrine action of cytokines?

  Binding to target cells in distant body parts
• What are the characteristics of cytokines?

  • Pleiotropy
  • Redundancy
  • Synergy
  • Antagonism
  • Cascade induction

  
• What does pleiotropy mean in cytokines?

  A cytokine has different effects on different cells

  
• What does redundancy mean in cytokines?

  Two or more cytokines mediate similar functions

  
• What is cytokine synergism?

  Combined effect of two cytokines enhances activity
• What is antagonism in cytokines?

  One cytokine inhibits the effects of another
• What is cascade induction in cytokines?

  One cytokine induces production of other cytokines

  
• What are the classifications of cytokines?

  • Interferons
  • Interleukins
  • Chemokines
  • Tumor necrosis factor
  • Growth factors
  • Colony stimulating factors

  
• What is the role of interferons in infection?

  First line of resistance to many viruses
• What do interferons activate?

  Immune cells like natural killer cells
• How do interferons increase recognition of infected cells?

  By up-regulating antigen presentation to T lymphocytes
• What symptoms are related to the production of interferons during infection?

  Aching muscles and fever
• What is the mediator of immune response?

  INF Ƴ
• How are human interferons classified?

  • Type I: IFN-α, IFN-β, IFN-ω
  • Type II: IFN-γ

  
• What are interleukins primarily produced by?

  T cells and mononuclear phagocytes
• What was the original description of interleukins?

  Signals for communication between white blood cells
• What is the primary function of interleukins?

  Directing cells to divide and differentiate

  
• How many well-known interleukins are there?

  35
• What is the function of INTERLEUKIN-1?

  Stimulates T-cells and B cell proliferation

  
• What is the role of INTERLEUKIN-2?

  Major activator of T and B cells

  
• What does INTERLEUKIN-4 do?

  Induces B cell proliferation and antibody synthesis

  
• What is the function of INTERLEUKIN-3?

  Growth factor for bone marrow stem cells
• What is the role of tumor necrosis factors?

  Can cause cell death
• What is the best-known member of the TNF family?

  Tumor necrosis factor-alpha (TNF-α)

  
• What does TNF-α do?

  Causes cytolysis of certain tumor cell lines
• What is the role of CD27L?

  Induces proliferation of co-stimulated T cells
• What is the function of CD30L?

  Induces proliferation of T cells
• What does FASL do?

  Involved in cell death
• What are colony-stimulating factors (CSFs)?

  • Secreted glycoproteins
  • Direct division and differentiation of bone marrow stem cells
• What are the types of CSFs?

  CSF1, CSF2, CSF3