Lec 1

• What are antigens?

  Substances that combine with an antibody
• What is an antibody?

  A protein that binds to antigens
• What are epitopes?

  Single antigenic determinants that combine with antibodies
• What factors contribute to the immunogenicity of an antigen?

  • Chemical structure of antigen
  • Degree of foreignness
  • Number of antigens introduced
  • Route of administration
  • Size of molecules (greater than 10,000 daltons)
• Which type of macromolecule is the most immunogenic?

  Protein
• What type of antibody is produced by antigens composed of oligosaccharides?

  IgM type of antibody
• What type of antibody is produced by antigens that are primarily protein in nature?

  IgG antibody
• How does the degree of foreignness affect immune response?

  The greater the difference from self, the greater the likelihood of eliciting an immune response
• What routes of administration are generally better for eliciting an immune response?

  Intramuscular or subcutaneous routes
• What is the minimum molecular weight for a molecule to be a better immunogen?

  Greater than 10,000 daltons
• What are the types of antigen-antibody reactions?

  • Agglutination
  • Sensitization
  • Haemolysis
  • Neutralization (inhibition)
  • Precipitation
• What is the equivalence point in agglutination reactions?

  The point at which the amount of antigen and antibody are optimal for visible reaction
• How should agglutination reactions be read or graded?

  By gently shaking the tubes and observing the cell button as it is dispersed
• What should be avoided when reading agglutination reactions?

  Hard shaking of the tubes
• What indicates hemolysis in agglutination reactions?

  Discoloration of the supernatant
• What are the grading descriptions for agglutination reactions?

  • Negative (-): No aggregates
  • Weak (+/-): Tiny aggregates, turbid and reddish supernatant
  • 1+: A few small aggregates, turbid and reddish supernatant
  • 2+: Medium-sized aggregates, clear supernatant
  • 3+: Several large aggregates, clear supernatant
  • 4+: One solid aggregate, clear supernatant