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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. Surface Barriers in Fish.
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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
Surface Barriers in Fish • Fish Skin, and Scales • Mucus • Lysosymes – act on microorganisms
Phagocytosis phagosome forming damage and digestion lysosome phagocytosis Release of microbial products lysosome fusion
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 phagocyte bacteria bacteria 2. chemotaxix 1. lysis 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 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 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
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
Antibodies (Immunoglobulin)in fish Binding sites Bacteria or virus
Clonal Selection Antigen selection B cells Proliferation/ maturation Production of antibody 2 Memory cells Plasma cells
Primary and secondary response Memory Immune response Antibody Memory Antibody Time Natural infection or booster Primary vaccination
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 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
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
Factors Affecting Immune Response • Intrinsic Fish • Extrinsic factors -