Download SELF DEFENSE SYSTEMS

Immunology
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• NON-SPECIFIC RESPONSES
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• SPECIFIC RESPONSES
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Immune System and Response
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• Immune Response
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Immune systems
• Parts of the system (systemic)
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• 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
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• Mucus
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• Lysosymes – act on microorganisms
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Phagocytosis
phagosome forming
lysosome
phagocytosis
lysosome fusion
damage and digestion
Release of
microbial products
Body fluid Barriers
• Complement
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• Transferrin
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• 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
Complement functions
complement
bacteria
1. lysis
phagocyte
2. chemotaxix
bacteria
3. opsonization
Immune System Cells
• Phagocytes–
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– neutrophils
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• 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)
Specific Immune System
• Antigen processing by Immunocompetent
cells (APC)
– Cellular
– Humoral immunity
• soluble antibody
– Lymphocytes “T or B” cells
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
Immune Response
Ant. Kidney
Thymus
Liver
stem cell
Macrophage
with antigen
Spleen
T cell
B cell
Fish IgM
Mammals
IgA
IgE
IgD
Plasma
Cell
IgG Humoral
Immunity
Memory
Cell
Activated
T cell
Cell mediated
Immunity
Antigen Presentation
Activated T-cell
Resting T-cell
IL-2, IL-4
Activation
IL-4, IL-5
TCR
IL-1
signal
CD4
CD3
MHC
B-cell
antigen
B cell T cell
epitope epitope
Accessory cell
Ig
synthesis
Antibodies (Immunoglobulin)
in fish
Binding
sites
Bacteria or virus
Clonal Selection
Antigen selection
B
cells
Proliferation/
maturation
Production of
antibody 2
Plasma cells
Memory
cells
Immune response
Primary and secondary response
Memory
Antibody
Antibody
Memory
Time
Primary
vaccination
Natural infection
or booster
Antibodies
• Protein or Antigen
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• Structure
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
Antibody heterogeneity between vertebrates
Vertebrate
group
Ab
IgM
synthesis
IgG/Y
IgA
Mammals
Birds
Reptiles
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Frogs/toads
Salamanders
/newts
Lungfish
Teleost fish
Sharks/rays
Jawless fish
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IgD
IgE
Vaccination
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• Many vaccines have non-specific
adjuvant that results in release of
interleukines/cytokines and stimulatory
factors
Anamestic Response
• Primary response
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• Cell mediated immunity
• Secondary Response
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Factors Affecting Immune Response
• Intrinsic Fish
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• Extrinsic factors –
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