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Immunology (elective) MLIM-101

Immunology (elective) MLIM-101. Prepared by: Dr. Mohamed S. Abdel- Latif. Learning Outcome:. At this time you should know the following: 1. To compare and contrast immunogen , antigen and hapten 2. To describe the factors influencing immunogenicity

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Immunology (elective) MLIM-101

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  1. Immunology (elective)MLIM-101 Prepared by: Dr. Mohamed S. Abdel-Latif

  2. Learning Outcome: At this time you should know the following: 1. To compare and contrast immunogen, antigen and hapten 2. To describe the factors influencing immunogenicity 3. To define the chemical nature of immunogens 4. To compare the structures of T-independent and T-dependent antigens 5. To introduce the concept of hapten-carrier conjugates and to describe their structure 6. To characterize antigenic determinants 7. To introduce the concepts of superantigens, PAMPs and PRRs

  3. Antigens

  4. Overview of the Immune System

  5. Definitions • Immunogen • Antigen (Ag) • Hapten • Epitope or Antigenic Determinant • Antibody (Ab)

  6. Sequence determinants Conformational determinants Factors Influencing ImmunogenicityContribution of the Immunogen • Foreignness • Size • Chemical Composition • Primary Structure • Secondary Structure • Tertiary Structure • Quarternary Structure

  7. Factors Influencing ImmunogenicityContribution of the Immunogen • Foreigness • Size • Chemical Composition • Physical Form • Particulate > Soluble • Denatured > Native

  8. Factors Influencing ImmunogenicityContribution of the Immunogen • Foreigness • Size • Chemical Composition • Physical Form • Degradability • Ag processing by Ag Presenting Cells (APC)

  9. Factors Influencing ImmunogenicityContribution of the Biological System • Genetics • Species • Individual • Responders vs Non-responders • Age

  10. Factors Influencing ImmunogenicityMethod of Administration • Dose • Route • Subcutaneous > Intravenous > Intragastric • Adjuvant • Substances that enhance an immune response to an Ag

  11. Chemical Nature of Immunogens • Proteins • Polysaccharides • Nucleic Acids • Lipids • Some glycolipids and phosopholipids can be immunogenic for T cells and illicit a cell mediated immune response

  12. Types of AntigensT-independent • Polysaccharides • Properties • Polymeric structure • Polyclonal B cell activation • Yes -Type 1 (TI-1) • No - Type 2 (TI-2) • Resistance to degradation • Examples • Pneumococcal polysaccharide, lipopolysaccharide • Flagella

  13. Types of AntigensT-dependent • Proteins • Structure • Examples • Microbial proteins • Non-self or Altered-self proteins

  14. Haptenic determinants Native determinants Hapten-carrier conjugates • Definition • Structure • native determinants • haptenic determinants

  15. Antigenic Determinants Recognized by B cells and Ab • Composition • Proteins, polysaccharides, nucleic acids • Sequence (linear) determinants • Conformational determinants • Size • 4-8 residues

  16. Fe Antigenic Determinants Recognized by B cells and Ab • Composition • Size • Number • Limited (immunodominant epitopes) • Located on the external surfaces of the Ag

  17. Antigenic DeterminantsRecognized by T cells • Composition • Proteins (some lipids) • Sequence determinants • Processed • MHC presentation (lipid presentation by MHC-like CD1) • Size • 8 -15 residues • Number • Limited to those that can bind to MHC

  18. Superantigen Conventional Antigen Polyclonal T cell response 1:4 - 1:10 Superantigens • Definition Monoclonal/Oligoclonal T cell response 1:104 - 1:105

  19. Superantigens • Definition • Examples • Staphylococcal enterotoxins • Staphylococcal toxic shock toxin • Staphylococcal exfoliating toxin • Streptococcal pyrogenic exotoxins

  20. Determinants Recognized by the Innate Immune System • Adaptive Immune System – Discrete Determinants • Reacts with a specific pathogen • Innate Immune System – Broad Molecular Patterns • Reacts with a variety of pathogens

  21. Determinants Recognized by the Innate Immune System • PAMPs – Pathogen Associated Molecular Patterns • PRRs – Pattern Recognition Receptors

  22. Assignment: As a part of the semester activity, group of students are selected every week to prepare a short seminar about his/her point of interest in one of the lecture topics. That to be discussed and evaluated during the next lecture.

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