Immune System Overview

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Immune System Overview
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GOT DEFENSE?
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ANATOMY OF THE IMMUNE SYSTEM

• The immune system is localized in several parts
  of the body
• immune cells develop in the primary organs - bone
  marrow and thymus
• immune responses occur in the secondary organs

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IMMUNITY
Adaptive
Innate
Players
Humoral
Cell-Mediated
Players
Macrophages Granulocytes Natural killer
cells Complement Other chemicals
Antigen Presenting Cells T cells B
cells Antibodies
Characteristics
Characteristics
Action requires days to develop Response is
specific Prevents progression to disease
Response is enhanced on repeated exposure to
pathogen
Action is immediate minutes to hours Response
is nonspecific First line of defense against
invading pathogens Response is not enhanced on
repeated exposure to pathogen
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Immune System Innate and Adaptive
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Cytokines

• Soluble protein molecules used by cells of the
  immune system to communicate.
• Functions include
• Mediation of natural immunity
• Regulation of lymphocyte activation, growth, and
  differentiation
• Regulation of immune-mediated inflammation
• Stimulation of immature leukocyte growth and
  differentiation
• Interleukins (IL-2 IL-4), interferons (a,ß,?),
  tumor necrosis factors (a and ß), and
  transforming growth factor ß

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Immune System Innate and Adaptive
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2. The immune system consists of

• Anatomic barriers (Skin,mucous membranes)
• Physiological barriers (temperature, pH)
• Phagocytic Barriers (cells that eat invaders)
• Inflammatory barriers (redness, swelling, heat
  and pain)

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Neutrophil
Eosinophil
Basophil
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Monocytes
Dendritic cell
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Immune System Innate (phagocytosis)

• 1. Phagocytic cells Macrophage, Neutrophil, and
  Dendritic cells.
• 2. Phagocytosis serves two key functions
• Killing microbes
• Antigen (Ag) Presentation

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GOT DEFENSE?
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Immune System Innate (phagocytosis)
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Opsonization
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Immune System Innate

• Inflammation
• A hallmark of innate immunity
• Local accumulation of immune cells and
  molecules against
• microbes
• Function to eliminate infections but often
  cause tissue
• damage diseases

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Inflammatory Response
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Inflammation
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Inflammatory Response
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The immune system consists of

• Antigen specificity
• Diversity
• Immunological memory
• Self/nonself recognition

• Anatomic barriers (Skin,mucous membranes)
• Physological barriers (temperature, pH)
• Phagocytic Barriers (cells that eat invaders)
• Inflammatory barriers (redness, swelling, heat
  and pain)

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Adaptive Immunity
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Major Histocompatibility Complex (MHC)

• Also known as Human Leukocyte Antigen (HLA)
• Membrane bound, not soluble
• Present processed protein antigens (peptides)
  to naïve T cells
• MHC I -gt produced by almost all nucleated cells,
  present antigen to CD8 cytotoxic T lymphocytes
  (CTL)
• MHC II -gt produced by professional antigen
  presenting cells, present antigen to CD4
  lymphocytes (T helper cells)

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T Cell Receptors (TCRs)

• Produced by T lymphocytes
• Are surface bound, not secreted
• Recognize processed peptide antigens presented
  on MHC molecules
• Heterodimer of aß or ?d chains
• Like antibodies, each chain has a variable and
  constant region
• Also undergo gene rearrangement prior to
  expression

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• The immune system has evolved to
• Protect against invading pathogens or
• foreign substances.
• Maintain tissue homeostasis.
• Meanwhile, microbes have evolved to
• survive in the host.