Antigen AND Immunogen and Antibodies

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Antigen AND Immunogen and Antibodies
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Definitions

• Immunogen
• Antigen (Ag)
• Hapten

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Factors Influencing ImmunogenicityContribution
of the Immunogen

• Foreigness
• Size
• Chemical Composition
• Physical Form
• Degradability

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Factors Influencing ImmunogenicityContribution
of the Biological System

• Genetics
• Responders vs Non-responders
• Age

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Factors Influencing ImmunogenicityMethod of
Administration

• Dose
• Route
• Subcutaneous gt Intravenous gt Intragastric
• Adjuvant
• Substances that enhance an immune response to an
  Ag

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Chemical Nature of Immunogens

• Proteins
• Polysaccharides
• Nucleic Acids
• Lipids
• Some glycolipids and phospholipids can be
  immunogenic for T cells and ellicit a cell
  mediated immune response

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Types of AntigensT-independent

• Polysaccharides

• Properties
• Polymeric structure
• Polyclonal B cell activation
• Resistance to degradation

• Examples
• Pneumococcal polysaccharide, lipopolysaccharide

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Types of AntigensT-dependent

• Proteins

• Structure

• Examples
• Microbial proteins
• Non-self or Altered-self proteins

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Antigenic Determinants Recognized by B cells and
Ab

• Composition
• Proteins, polysaccharides, nucleic acids,
  haptens
• Sequence (linear) determinants
• Conformational determinants
• Size

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Antibody
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Ab structure
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Ab structure
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Antibody
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Ab structure
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Ab Isotypes
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IgA
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