Major histocompatibility complex

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Major histocompatibility complex. MHCs: The Role of Cell Surface Markers. MHC- Major Histocompatibility complex. Immunity = ability to distinguish between "self" and "non-self” Every cell carries same set of distinctive surface proteins distinguish you as "self”
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Major histocompatibility complexMHCs: The Role of Cell Surface MarkersMHC-Major Histocompatibility complex
  • Immunity = ability to distinguish between "self" and "non-self”
  • Every cell carries same set of distinctive surface proteins
  • distinguish you as "self”
  • Pattern is unique to individual
  • Set of unique markers on human cells = major histocompatibility complex (MHC).
  • Immune response
  • Respond against/eliminate foreign agents
  • Protein toxin molecule
  • Virus
  • Infectious bacterium
  • Lack of MHC = Lack of immune response
  • histocompatilibity
  • Similarity of patterns of MHC molecules
  • Skin grafts
  • Tissue/organ transplants
  • Organ transplants
  • Both individuals examined for genetic similarity
  • Blood group & MHC molecules
  • 10/12 matches
  • Medicine to lower immune response
  • MHC Class I/II
  • Inherit 2 of each class (MHC I/II)
  • 1 from Mom
  • 1 from Dad
  • Both sets of Class I or Class II OR sometimes both are expressed on cell surface
  • Induction of immune response of invader
  • Class (I/II) expressed on surface depends on type of cell involved
  • MHCsWhich cells express MCH i/ii?
  • All nucleated cells = equally express BOTH sets of just MCH I
  • Antigen-Presenting Cells
  • Some specialized cells of immune system = express BOTH sets of MCH I AND MCH II
  • B-lymphocytes
  • Macrophages
  • Certain dendritic cells
  • Capacity to express MHC Class II molecules  known as Antigen-Presenting Cells (APC)
  • Antigen-Presenting Cells
  • Can present parts of proteins taken up by the ACP to T lymphocytes.
  • Non-specific mechanism
  • First line of defense
  • Physical barriers of the body
  • Skin
  • Mucous
  • Tears
  • Saliva
  • pH of skin
  • Non-specific mechanism
  • 2nd line of defense
  • White blood cells + inflammatory response
  • Phagocytosis (Neutrophils, macrophages, eosinophils)
  • Inflammation = blood supply increased in injured area (redness, heat)
  • Swelling = histamine released by basophils and mast cells, triggers inflammatory response
  • Specific immune mechanism
  • Recognizes SPECIFIC foreign material and destroys it
  • Antibodies, Killer T cells
  • Active vs. Passive immunity
  • Active = develops after recovery disease or vaccination
  • Chicken pox, vaccinations (measles, mumps, rubella)
  • Passive = passed from one individual to another
  • NOT PERMANENT!Ex: Breast-feeding passes immunities to child
  • 2 types of responses to antigens1. Humoral immunity-B Cell activation -Production of antibodies2. Cell-mediated response - Production of Cytotoxic T CellsHumoral IMMUNE RESPONSE
  • Antibodies produced
  • Bind to antigens = easier targets for phagocytes.
  • Mainly free bacteria, toxins, viruses in body fluids
  • Humoral responseHumoral Response
  • T-Cell (Helper T Cell)
  • Specifically interacts with MHC II shapes produces cytokines
  • Cytokines (IL-2) stimulate activated B cells to produce antibodies
  • Now, anywhere toxin is in system… engulfed by macrophages!
  • Cytokines
  • Secreted proteins + signaling molecules
  • Interleukin
  • promote development and differentiation of T & B cells
  • Interleukin-1 (IL-1)
  • Inflammatory response (fever)
  • Macrophage secretes IL-1 after presenting antigen
  • IL-1 + presented antigen  Activates helper T Cell to produce IL-2
  • Cytokines
  • Secreted proteins + signaling molecules
  • Interleukin
  • promote development and differentiation of T& B cells
  • Interleukin-1 (IL-1)
  • Inflammatory response (fever)
  • Macrophage secretes IL-1 after presenting antigen
  • IL-1 + presented antigen  Activates helper T Cell to produce IL-2
  • Interleukin-2 (IL-2) “The Recruiter”
  • Helps B cells that have contacted antigen to differentiate into antibody-secreting plasma cells
  • Helps Cytotoxic T cells become active killers
  • Cell Mediated Immune Response
  • Cytotoxic T cells (Killer T cells) produces killer substances
  • Active against viruses/bacteria within infected cells
  • Will be eliminated from the body
  • Depends on MHC Class I AND II
  • Cell Mediated immune response
  • Viral proteins associate with MHC I
  • Transported to surface
  • Recognized by cytotoxic T cell (Killer T Cell)
  • Binds to specific fragment shape of MHC I and foreign protein shape (FITS TO ONLY FOREIGN)
  • ACTIVATES AND PREPARES KILLING SUBSTANCES
  • Waits for permission from Helper T cell
  • Cell mediated response
  • Helper T Cell
  • Activated by interaction of APC (Antigen Presenting Cell) presenting fragments via MCH II molecules
  • Just like in Humoral Response!
  • Helper T Cell releases cytokines (IL-2)
  • SIGNALS KILLER T CELL TO RELEASE THE KILLING SUBSTANCES!
  • Kills cell that contains virus
  • Eventually rid body
  • Organ transplants
  • MHC Class I / II expressed on surface of tissue
  • Different shapes than our own
  • Recognized by helper and killer T cells
  • See it as out own MHC molecules “presenting” foreign fragments
  • Perceived as our own tissue that is “infected”
  • REJECTION-IMMUNE SYSTEM ATTACKS!
  • 10/12 MHCs must match
  • Immunosuppressant medication
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