Immunology

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Immunology

• NON-SPECIFIC RESPONSES
• SPECIFIC RESPONSES

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Immune System and Response

• Immune Response

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Immune systems

• Parts of the system (systemic)
• Mucosal immune system

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Non-specific immune system

• Very Important in fish
• Logical, due to aquatic environment

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Surface Barriers in Fish

• Fish Skin, and Scales
• Mucus
• Lysosymes act on microorganisms

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Phagocytosis
phagosome forming
damage and digestion
lysosome
phagocytosis
Release of microbial products
lysosome fusion
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Body fluid Barriers

• Complement
• Transferrin
• Interferon

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Signaling (soluble mediators)

• Complement (innate/adaptive responses) Group of
  serum proteins that function in the control of
  inflammation
• Alternative pathway (innate) Complement
  molecules coat microorganism
• Acute phase proteins
• Spontaneously activated
• Classical pathway (adaptive) Complement
  molecules activated by antibodies bound to
  pathogen (cascade)
• Cytokines Group of molecules involved in
  signalling between cells during immune response

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Complement functions
complement
phagocyte
bacteria
bacteria
2. chemotaxix
1. lysis
3. opsonization
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Immune System Cells

• Phagocytes-
• neutrophils
• Natural killer cells

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Immune cells (innate immunity)

• Phagocytic Leucocytes (also involved in adaptive
  responses) Function to engulf particles,
  including infections agents, internalize and
  destroy them
• Monocytes Blood cell lineage found in
  circulation
• Macrophages Monocytes which have migrated into
  the tissues
• Neutrophils Ingest and lyse pathogens
  (lysozyme, acid hydrolases, etc)

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Specific Immune System

• Antigen processing by Immunocompetent cells (APC)
• Cellular
• Humoral immunity
• soluble antibody
• Lymphocytes T or B cells

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Specific responses (Adaptive immunity)

• Lymphocytes Initiate adaptive immune responses
  (derived from stem cells in anterior kidney of
  fish)
• B-cells Responsible for producing antibody
• T-cells Cytotoxic functions as well as helper
  functions for antibody production
• Antigen Any molecule that can be recognized by
  B and T cells
• Antibody (Immunoglobulin) Serum proteins that
  recognize a specific antigen

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Immune Response
Ant. Kidney
Thymus
Liver
stem cell
T cell
Macrophage with antigen
Spleen
B cell
IgM
Fish
Activated T cell
Plasma Cell
IgA
Memory Cell
IgE
Mammals
IgD
Cell mediated Immunity
IgG
Humoral Immunity
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Antigen Presentation
IL-2, IL-4
Activated T-cell
Resting T-cell
Activation
IL-4, IL-5
TCR
CD3
IL-1 signal
CD4
Y
MHC
Y
B-cell
antigen
Y
Y
Y
Y
T cell epitope
B cell epitope
Y
Accessory cell
Ig synthesis
Y
Y
Y
Y
Y
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Antibodies (Immunoglobulin)in fish
Binding sites
Bacteria or virus
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Clonal Selection
Antigen selection
B cells
Proliferation/ maturation
Production of antibody 2
Memory cells
Plasma cells
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Primary and secondary response
Memory
Immune response
Antibody
Memory
Antibody
Time
Natural infection or booster
Primary vaccination
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Antibodies

• Protein or Antigen
• Structure

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Antibody production

• T - cells proliferate and release lymphokines, B
  (memory) cells have different Ig receptors on
  cell surface that are activated
• B cells multiply, release immunoglobins in plasma

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Immune System

• Mammals vs Fish
• Mammals
• Very advanced leading to long term protection
• Ig isotype heterogeneity
• Distinct mucosal and systemic (internal) immune
  systems
• Fish
• More primitive shorter duration and less
  specific
• Limited Ig isotype repertoire
• Importance of specific mucosal responses not well
  known

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Antibody heterogeneity between vertebrates
Vertebrate group Ab synthesis IgM IgG/Y IgA IgD IgE
Mammals
Birds
Reptiles ?
Frogs/toads
Salamanders/newts
Lungfish
Teleost fish ?
Sharks/rays
Jawless fish
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Vaccination

• Many vaccines have non-specific adjuvant that
  results in release of interleukines/cytokines and
  stimulatory factors

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Anamestic Response

• Primary response
• Cell mediated immunity
• Secondary Response

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Factors Affecting Immune Response

• Intrinsic Fish
• Extrinsic factors -