1 / 28

Antigens, Immunogens , Epitopes, and Haptens

Antigens, Immunogens , Epitopes, and Haptens. Innate and adaptive immunity:. Innate (Natural) Immunity:. Inborn resistance. present the first time a pathogen is encountered (does not require prior exposure) Usually not specific not modified by repeated exposure to the pathogen.

tadita
Download Presentation

Antigens, Immunogens , Epitopes, and Haptens

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Antigens, Immunogens , Epitopes, and Haptens

  2. Innate and adaptive immunity:

  3. Innate (Natural) Immunity: • Inborn resistance. • present the firsttime a pathogen is encountered (does not require prior exposure) • Usually not specific • not modified by repeated exposure to the pathogen.

  4. Adaptive (Acquired) Immunity: • weak or absent at the first exposure. • specific • increases dramatically with subsequent exposures to the same pathogen(Memory)

  5. Types of innate immunity: • Humoral (soluble)immunity • Cell mediated immunity • Types of adaptive immunity • Humoral (soluble)immunity • Cell mediated immunity

  6. Soluble mediators of innate immunity: • Proteins and enzymes • Cytokines & type 1 interferons. • Complement

  7. Proteins and enzymes • A variety of proteins and enzymes (present in human blood and tissue fluids) are considered the first part of innate immunity. • Example: C reactive protein (CRP), lysozymes, and defensins.

  8. n Cytokines, and Type I interferons: Cytokines: IL-1, IL-6, IL-12, and TNFα produced by activated phagocytes. Type I interferons: • IFN-α produced by dendritic cells • IFN-β Produced by fibroblasts. -INFs are rapidly produced, within minutes by the infected cells (virus infection).

  9. Cells of Innate immunity: • Phagocytes: - Monocytes and macrophages: blood stream andtissues. - Dendritic cells: lung, and GIT mucosa. • Granular leukocytes: -Neutrophils, and eosinophils. -Basophils and mast cells. • Natural killer cells (NK).

  10. Adaptive Immunity: • Soluble mediators of adaptive immunity: - Cytokines: IL-2, IL-3, IL-10,IL-13. - Interferons: INF-γ (Gamma). - Complement. • Soluble and cell-bounded proteins: -The Immunoglobulins. • Immune cells: - T lymphocytes - B lymphocytes - N.K cells.

  11. Cytokines: IL1, IL6, IL12 & TNFα. Interferons: IFα and IFβ. Complement Cytokines: IL2, IL3, IL10 & IL13. Interferons: IFγ Immunoglobulins. • n Phagocytes: monocytes, MQ & DC Granular leukocytes T lymphocyte & B lymphocytes NK cell

  12. n

  13. Antigens, Immunogens , Epitopes, and Haptens

  14. Antigen: Is a molecule or part of a molecule that is recognized by the immune system. Immunogen: Is an antigen that evokes a specific, positive immune response.

  15. Example: Injecting a laboratory animal by human chromosome Anti-DNA antibodies and anti-HistonsAntibodies will be produced.

  16. Immunogenicity and Properties of immunogen: • Immunogenicity is the ability of immunogen to activate immune response. • Properties of Immunogen: • Foreignness • Size • chemical nature and complexity.

  17. Foreignness: Immune system can discriminate between foreign and self substance (self & non self) • Size: Molecular weight of at least 10,000 Dalton. • Chemical nature: -Mainly proteins (polypeptide) -Carbohydrates, steroids, and lipids are poor immunogens.

  18. n Chemical complexity: • As the chemical complexity increases; the immunogenicity increases. • Homopolymersare poor immunogens regardless of size, while heteropolymers are strong immunogens. • Proteins are heteropolymers (different amino acids)

  19. n Epitopes (The Antigenic determinants): • The smallest part of an antigen or immunogen that can be recognized by the B & T cells receptors.So it is the basic recognition element. • A single antigen molecule may have several different epitopes. • Immunodominantepitope is an epitope that can stimulate a greater antibody response than others.

  20. N epitopes

  21. B cell receptors can recognize epitopes whether they are: • free soluble molecules. • Surface-bound molecules. • Degraded fragments. • T cell receptors can bind only to epitopes which are surface-bound molecules.

  22. Superantigen: • is a substance such as a bacterial toxin that is capable of stimulating multiple T lymphocytes, leading to release of relatively large quantities of cytokines.

  23. n

  24. Hapten: Small, non-biologic molecules that bind to immune cells receptors but cannot by themselves induce a specific immune response.

  25. (Land-Steiner’s experiment). Injected a mice with: • hapten No immune response • carrier (protein) Anti carrier • Hapten + Carrier Anti-Hapten + Anti-Carrier

  26. T-cell dependent and T-cell independent Antigens: • Antigens are classified as either T-cell dependent or T-cellindependent. • T cell dependent antigen activates immune system depending on T-lymphocytes.

More Related