Immunology

• Microbe or microorganism


  • Need a microscope to visualise
  • Can cause disease-damage or injury
• Kennel Cough


  Can be prevented by vaccination
• Vaccinated dogs can still become infected but may not show full symptoms
• Immunity


  Body's ability to fight disease and infection
• Recognition and removal of self and non-self (antigen)

  Has to be able to recognise what is self and non-self in order to protect body from foreign material and to stop it hurting healthy cells
• Auto-immune disease


  When body confuses self and non-self
• Auto-immune diseases


  • Lupus, rheumatoid arthritis
• Immune system


  System of interacting cell populations and molecular networks triggered by the presence of foreign invaders
• Immune system functions


  • Initial recognition of foreign substances
  • Production of effector molecules and cells that eliminate the pathogens
• Immunity against disease


  Does not mean an individual cannot contract it, means that they are more readily able to fight the disease
• Even though the individual may contract the disease, they may be asymptomatic or have lessened symptoms
• Vaccines and anti-serums


  Provide immunity against disease
• Cells involved in immunity

  • Blood- plasma (extra-cellular)
  • Blood - erythrocytes, leukocytes, platelets (cellular)
• Plasma


  90% water, contains proteins like albumin, globulin, fibrinogen
• White blood cells (leukocytes)

  • Nucleated cells-granular or clear cytoplasm
  • Agranular (clear) - lymphocytes, monocytes
  • Granular - neutrophils, eosinophils, basophils
• Lymphocytes


  Produce antibodies
• Eosinophils


  Involved in allergic reactions, parasites
• Basophils


  Involved in inflammation, allergic reaction
• Blood cell counts


  • RBCs normally expressed as haematocrit (PCV)
  • WBCs normally expressed as ratios of total WBC count
• Differential cell count


  Practical class
• Systems of defence


  • Innate immunity - non-specific, involves basics, neutrophils and macrophages
  • Adaptive immunity - highly specific, involves lymphocytes and antibodies
• Invading pathogen


  1. Physical barriers (skin)

  2. Focused response - inflammation

  3. Specific immunity - adaptive
• Innate immunity


  Natural, non-specific, first line of defence
• Innate immunity components


  • Physical barriers (skin, secretions)
  • Behavioural (coughing, vomiting)
  • Focused response
• Physical barriers


  Ears wax, eyes-tears-enzymes, intestine-acid barrier, reproductive system-acid secretions, excretory system-flushing of urine, respiratory system-nose, cilia, mucous
• Mucus


  Found in most body openings, serves 2 purposes: mechanical cleansing, contains microbial agents
• Lymphoid organs


  • Primary - bone marrow, thymus
  • Secondary - lymph nodes, spleen, tonsils, tissue in mucous membranes
• Microbiome


  Microorganisms on body surface and within body, some are beneficial, others have no known effects, most do not cause disease but may help maintain good health
• Phagocytosis


  Process where phagocytic cells (neutrophils, macrophages) engulf and destroy antigens
• Soluble factors


  Complement, acute phase proteins, interferons
• Complement activation


  1. Classical activation - C1 activated by Ab, binds to Ag-Ab complex

  2. Alternative activation - bacteria, parasites activate C3, triggers rest of complement cascade
• Opsonisation


  Occurs when complement cascade is activated, facilitates phagocytosis
• Acute phase proteins


  Plasma proteins that increase or decrease in response to inflammation, involved in mediating fever
• Interferons


  Glycoproteins made and released by lymphocytes, prevent antigen replication, stimulate NK cells
• Cytokines


  Soluble proteins involved in cell-to-cell signalling, released from cells in response to antigen contact, stimulate or attract components of immune system
• Acquired immunity


  Specific, adaptive, immunity acquired following previous exposure, involves lymphocytes and antibodies
• Acquired immunity


  • Specificity, memory, ability to amplify response
• Components of acquired immunity

  • Antibodies - large protein molecules that bind to antigen and facilitate its destruction
  • Lymphocytes - cellular reactions
• Antibody functions


  Primary defense, neutralisation, opsonisation, crosses placenta to provide foetal immunity
• Clinical significance of antibodies

  Diagnostics, vaccination, crucial for vaccine effectiveness