Immunology

• 80% of periodontal destruction is due to host immune response rather than bacteria directly
• Bacteria starts the perio disease process but the immune system collapsing causes the effect eg bone loss. The bodies response causes the damage.
• What is an Immunoglobulin?

  An antibody

  Produced by plasma cells

  5 classes of immunoglobulins
• When B lymphocyte meets its specific antigen, it proliferates anddifferentiates Creates plasma cells Memory cells All the plasma cells will be producing an antibody to the antigen Individual cells will either produce IgG or IgA or IgM or IgD or IgEantibodyThe relative number of cells producing antibody:IgG>IgA>IgM>IgD>IgE
• What is the primary response?

  When the body hasn't seen or meet a certain bacteria or virus
• What is the secondary response?

  The body has meet/defeated the bacteria or virus before and has some form of antibody
• IgA Occurs in two different forms:1 It is found in serum where it cannot activate the complementsystem2. Secretory IgA is found in the seromucous secretions of therespiratory and gastrointestinal surfaces and in sweat, tears, salivaand colostrumIt is referred to as the antiseptic paint of mucous membranesMay act by covering parts of pathogens, inhibiting their adherenceto surface mucosal cells, and hence their entry to the bodySecretory IgA can activate the complement system in thepresence of Lysozyme to kill some organisms
• IgM?


  -Largest of the immunoglobulin molecules-Earliest antibody response in a primary immune response, but it is short lived-Most natural antibodies, such as the blood group AB isoagglutinins are IgM class
• IgD?


  -Low levels in blood-Cannot activate the complement system-About half of the antigen specific receptors on B lymphocyte membranes are composed of IgD antibodies
• IgE?

  Found in very small amounts in serum Most IgE in the body is attached to mastcells and basophils High levels of circulating IgE are found inallergic individuals (e.g. those with asthma,hay fever etc.)
• What are the two main ways in which the complement system can be activated?

  The classical pathway

  The alternative pathway
• What does the classical pathway involve?

  Starts by activating complement factor C1 and then the others in more or less numerical order (C1,4,2,3,5-9)This is the mechanism adopted by the antigen-antibody complexesIgG and IgM can activate C1
• what does the alternative pathway involve?

   Replaces the first 3 factors of the classical pathway (C1, C4, C2,) with factors D and B which directly activate C3 Then follows same terminal stages as the classical pathway
• What does the activated complements cause?

  The release of histamine from mast cells

  Produces vasodilation, increases vascular permeability

  Broncho-constriction (wheezing)
• What is the role of complement?

  1. To increase blood flow and vascular permeability2. This allows antimicrobial factors in the blood to “leak” into the tissues3. Attracts polymorphs to the site4. Encouraging immune adherence and phagocytosis of the pathogens or foreign cells by the phagocytes
• what is cell mediated immunity involved in?

  1. Resistance to infections
  2. Tumour rejection
  3. Delayed hypersensitivity states
  4. Regulation of the immune system