immunology non-specific responses – specific responses –
Post on 20-Dec-2015
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Immunology
•
• NON-SPECIFIC RESPONSES–
• SPECIFIC RESPONSES– –
Immune System and Response
• –
• Immune Response– –
Immune systems
• Parts of the system (systemic)– – –
• Mucosal immune system– –
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– – –
phagosome forming
lysosome damage and digestion
phagocytosis lysosome fusion Release of microbial products
Phagocytosis
Body fluid Barriers
• Complement – –
• Transferrin –
• Interferon–
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 phagocyte bacteria
1. lysis 2. chemotaxix 3. opsonization
Immune System Cells
• Phagocytes-
– – – neutrophils
•
•
• Natural killer cells–
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 circulationMacrophages: Monocytes which have migrated into the tissuesNeutrophils: 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
IgMIgAIgEIgD
IgG
Mammals
FishPlasma
Cell
Spleen
Liver
Ant. KidneyThymus
T cell
B cell
Macrophagewith antigen
ActivatedT cell
Cell mediatedImmunity
HumoralImmunity
stem cell
MemoryCell
Antigen Presentation
Resting T-cell Activated T-cell
Accessory cell
B-cell
Ig synthesis
antigen
B cellepitope
T cellepitope
MHC
CD4 CD3TCR
Activation
IL-1signal
IL-2, IL-4
IL-4, IL-5
Antibodies (Immunoglobulin)in fish
Bindingsites
Bacteria or virus
Clonal Selection
Antigen selection
B cells
Proliferation/maturation
Plasma cells Memory cells
Production ofantibody 2
MemoryAntibody
Antibody
Memory
Imm
un
e re
spon
se
Primary vaccination
Time
Natural infectionor booster
Primary and secondary response
Antibodies
• Protein or Antigen–
• 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– –
Immune SystemMammals 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 synthesis
IgM IgG/Y IgA IgD IgE
Mammals
Birds
Reptiles ?Frogs/toads
Salamanders/newts
Lungfish
Teleost fish ?Sharks/rays
Jawless fish
Vaccination
•
• Many vaccines have non-specific adjuvant that results in release of interleukines/cytokines and stimulatory factors
Anamestic Response
• Primary response –
• Cell mediated immunity
• Secondary Response –
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Factors Affecting Immune Response
• Intrinsic Fish – – – –
• Extrinsic factors -– – – –