clinmedimmunity

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Author:
mdeguzman7
ID:
141892
Filename:
clinmedimmunity
Updated:
2012-03-21 00:01:46
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clinical med immunity
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Description:
Clin Med - Immunity
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  1. 2 Forms of Immunity
    • Cellular Response (lymphocytes - direct response, detect foreign cell/material)
    • Humoral Response (antibodies circulate in the blood)
  2. What are the 2 types of lymphocytes
    • B - Cells - (derived from bone marrow, matures in Butt?)
    • T- Cells - (originate from the bone marrow, matures in the Thymus)
  3. What do B-cells do?
    B-cells react when antibodies come into contact w/ antigen. B-cells differentiate into plasma cells. Plasma cells then produce antibodies specific for the antigen stimuli of original B-cell.
  4. What are the 5 processes of B-cell differentiation, maturation, and activation?
    • 1. pre-B cell: contain receptors on plasma membrane but no surface immunoglobulin (NO IDENTITY)
    • 2. early-B cell: immature... recognized by surface IgM and later IgD
    • 3. isotype switching: expression on the surface of other immunoflobulins - IgG, IgA, IgE
    • 4. mature B-cells: constitute 10-20% of pperipheral lymphocytes awaiting activation by foreign Antigen (sensitization) immunogl. isotypes IgG, IgM, IgA
    • 5. Plasma Cells: make antibodies, requires exposure to additional T-cell products but sometimes cytomegalovirus activation can be direct
  5. Specificity of B-cells and memory
    During activation B-cells dividing under modulation of T-cells, most of the new B-cells become a "selected clone" of the plasma cells and pump out specific antibodies.

    When the immune system "wins" the plasma cell dies, but plenty of the B-cell clones survive and have memory --> future presence of that same antigen will trigger greater antibody response
  6. What do T-cells do?
    • T cells DO NOT USE ANTIBODIES nor have them on their surfaces.
    • But specificity of the antigen recognition is guaranteed by the receptor presented on the plasma membrane.
    • Important for protection against Tumors, intracellular bacteria, viruses, parasites, and reactions to transplant
    • Centerpiece of immune system
  7. What are the 3 basic mechanisms for which most of T-cell functions?
    • 1. some are DIRECTLY CYTOTOXIC
    • 2. some participate in RELEASE of vaious CYTOTOXIC MEDIATORS
    • 3. some are involved in STIMULATION of B-Lymphocytes
  8. What are the different T-Lymphocyte subtypes?
    • CD4 - helper "commander"
    • CD8 - Cytotoxic "soldier"
    • CD3 - ???

    they're categorized by expression of specific surface marker proteins --> CD - cluster designations
  9. What are the 4 differentiations of T-lymphocytes?
    • Early cortical T-cells (least mature thymocytes, make up 10% of all T-lymphocytes)
    • Late cortical T-cells (thymocytes that account for 80% of thymic populsion
    • Medullary T-cells (CD-4 helper 50% and CD-8 Cytotoxic 50%, located in medulla of thymus)
    • Peripheral T-cells (T-lymphocytes released to the blood with 65% (Cd-4 helpers) and 35% (Cd-8 cytotoxic)
  10. What are natural killer cells (NK)?
    • 10-15% of Blood lymphocytes
    • NK's are the First line of defense vs neoplastic tumors and virus infected cells since they can lyse them without prior sensitization
    • special type of Large lymphocytes (formerly known as non-t/-non-B or NULL cells)
  11. What are hypersensitivity reactions and how are they classified?
    • They are immune responses to antigiens that can cause tissue damaging reactions
    • Resultant tissue lesions --> Hypersensitivity disease
    • They're classified on the basis of the mechanism mediating the disease
  12. Type I hypersensitivity
    • Mediated by IgE antibody sensitization
    • immune response release vasoactive mediators from MAST cells or Basophils that affect vascular permeability and smooth muscle
    • "ALLERGY reaction" --> activation of MAST cells, Basophils, releasing:
    • 1. Histamine as primary mediator
    • 2. Prostoglandins, lukotrienes as secondary mediators
    • Can be 1. LOCAL - (itching swelling sneezing, eyes and nasal)
    • 2. GENERALIZED - (bronchoconstriction, cirulatory collapse, Anaphylactic shock/syndrome)
  13. Type II hypersensitivity
    • IgG and IgM Mediated
    • Classes of antibody participate in indirect cytotoxicity
    • Antibodies binding to an antigen on surface of cells --> induce activation of COMPLEMENT which leads to target cell destruction by:
    • 1. DIRECT LYSIS (membrane attack complex C5-9)
    • 2. OPSONIZATION (enhancing phagocytosis (C3b)
    • Examples: (many autoimmune disease eg Hemolytic anemia, Graves disease, Myasthenia Gravis)
  14. Type III hypersensitivity
    • Antigen - Antibody Complex disease
    • Mediated IgM, IgG, IgA complexes formed in circulation and deposted in different tissues -->
    • presence acitivates complements, Chemotaxis (of neutrophils --> trigger acute inflam rxn impairing tissue fx
    • examples: SLE or Lupus
  15. TYPE IV hypersensitivity
    • cell-mediated immmune response (NO ANTIBODIES)
    • antigens are processed bt macrophages and presented to cytotoxic T-cells --> their activation relaease of mediators
    • --> destroying plasma membrane and target cells
    • examples: Sjorgen syndrome

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