Cells and Organs of the Immune System I and II Flashcards Preview

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Flashcards in Cells and Organs of the Immune System I and II Deck (31)
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describe antigen factors in immunogenicity

  • molecular size: generally > 100,000 Da
  • chemical composition:
    • greater complexity (heterogeneity) = greater immunogenicity
    • generally proteins > carbohydrates > lipids
    • susceptibility to processing and presentation
    • D-amino acids cannot be processed
  • adjuvant:
    • BSA in mice; alum in humans
    • generally increase persistence of antigen and innate response (inflammation, stimulation of APC and/or lymphocytes)


describe host factors in immunogenicity

  • genotype of host:
    • MHC gene products
    • B cell receptors
    • TCR
  • dosage and administration:
    • low doses may induce tolerance or fail to stimulate enough lymphocytes
    • boosters increase clonal selection
    • route: slow reelase is important for immune response:
      • subcutaneous > intraperitoneal > intravenous > intragastrical
      • oral route induce local mucosal immunity but not systemic immunity


summarize the factors that influence the immunogenicity of proteins


describe the innate arm of the immune system

  • molecular and cellular mechanisms preformed and fully active (immediate reaction)
  • non-specific
    • distinguishes between self and pathogens but not specialized to distinguish small differences in the foreign particles
  • components:
    • barriers that protect host
      • skin, including its usual skin flora
      • mucous membrane
      • acidity of stomach
      • lysozymes in fluids
    • phagocytic cells
    • antimicrobial peptides (interferons, complement)
    • temperature


describe the acquired (adaptive) arm of the immune system

  • develops in response to infection
  • adapts to recognize, eliminate, and remember pathogens
  • highly specific
  • takes several day for this arm to become fully functional
  • components: cell-mediated immunity and antibody-mediated (humoral) immunity


name the cellular and humoral components of the innate vs adaptive system


summarize the lineage of immune cells from a stem cell


summarize the CD markers on leukocytes


describe the APCs


describe the general activites of macrophages

  • to survey tissue compartments and discover microbes, particulate matter and dead or injured cells
  • to inget and eliminate these materials
  • to extract immunogenic information from foreign matter


describe neutrophils (granulocyte)

  • multi-lobed nucleus:  2-5 lobes
  • different granules
  • 1st to arrive at site of inflammation
    • high #'s is 1st indication of infection
  • destroy organisms by:
    • phagocytosis
    • release of hydrolytic enzymes
  • neutrophiles are very short lived (10 hrs in blood, 1-3 days in tissue)
    • come out of blood vessels ready to kill, would cause too much damage to tissues if long lived


describe eosinophils (granulocyte)

  • bilobed nucleus
  • located mainly in tissue
  • small central Golgi apparatus, and limited ER and mt
  • phagocytize
    • specific granules and azurophilic granules
    • specific granules (crystalloid):
      • inside: basic proteins, cationic protein, neurotoxin
      • outside: histaminase, peroxidase, cathepsin
  • functions:
    • play a role in elimination of parasitic helminths and allergic reactions
    • phagocytize antigen-antibody complexes


describe basophils (granulocyte)

  • bilobed, S-shaped nucleus
  • granules:
    • basophilic specific granules:
      • heparin, histamine, chemotactic factors, peroxidase
  • survive long periods of time (2 years in mice)
  • non-phagocytic
  • functions:
    • play a role in allergic reactions


describe mast cells (and 2 ways to activate them)

  • similar to basophils
  • play important role in development of allergies
  • two pathways for activation:
    • innate TLRs
    • antibody-dependent (IgE)


describe the function of the 3 classes of lymphocytes (T cells, B cells and NK cells)

  • T cells are involved in cell-mediated immunity (cellular immunity)
  • B cells are antibody-mediated immunity (humoral immunity) because antibodies circulate widely in body fluids
  • NK cells perform immune surveillance, attacking foreign cells, body cells infected with viruses and cancer cells 


describe B-lymphocytes (B-cells)

  • site of maturation
    • bone marrow in mammals
  • display membrane-bound immunoglobulin (antibody)
  • once antigen is encountered:
    • differentiation
    • plasma cells - antibody secreting cells, die within 1-2 weeks
    • memory B cells - same membrane-bound antibody as parent B cell, longer life span


describe T lymphocytes

  • site of maturation: thymus
  • T cell receptor
    • only recognize antigen (peptides) that is bound to cell membrane proteins called major histocompatability complex (MHC) 
    • once antigen is encountered with MHC: 
      • differentiation
        • effector T cells
          • T helper, T cytotoxic, T regulatory or T suppresor
        • memory T cells


describe T helper cells

  • mature Th cells express the surface glycoprotein CD4 and are referred to as CD4+ T cells
  • recognizes antigen presented in MHC class II (extracellular/phagocytized)
  • "help" activation of B cells, Tc cells, macrophages in immune response


describe T cytotoxic cells

  • mature Tc cells express the surface protein CD8 and are referred to as CD8+ T cells
  • recognizes antigen presented in MHC class I
    • eliminates virus/intracellular microbes infected cells or cancerous cells


describe T regulatory cells

  • mature T regulatory (suppressor) cells express the surface glycoprotein CD4, CD25 and FOXP3
  • help suppress the immune system after it's been upregulated after the infelction is cleared
  • maintain tolerance to self-antigens and prevent autoimmune diseases


describe memory T cells

  • T cells that have previously encountered and responded to their cognate antigen
  • at a second encounter with the invader, memory T cells can reproduce to mount a faster and stronger immune response
  • memory T cells may be either CD4+ or CD8+


name the 2 major cytokines of T regulatory cells (CD25)

IL-10 and TGF-B


summarize the functions of T cell types and their cytokines


describe natural killer cells

  • innate immune response
  • large, mononuclear, granular
  • surface markers CD16 (FcyRIII) and CD56


contrast humoral immunity and cell-mediated immunity


describe dendritic cells

  • long membranous extensions (stellar)
  • CD14+
  • 4 major groups:
    • lymphoid or plasmacytoid-derived DC
    • monocyte-derived or myeloid DC
    • Langerhans DC
    • follicular DC
      • no MHCII
      • different from above 3 types in fxn
  • functions:
    • surveillance
    • initiation of inflammatory response
    • stimulation of adaptive immune system
      • antigen processing and presentation
      • take a "snapshot" of what is happening in the tissues and carry this image to the lymph node


describe the bone marrow (primary lymphoid organ)

  • lymphocytes arise in the bone marrow
    • T cells go to thymus to mature
    • B cells mature in the bone marrow
      • 90% of plasma IgG and IgA comes from B cells in the bone marrow


describe the thymus (primary lymphoid organ)

  • T cell development and maturation
  • thymus will induce death of those T cells that can't:
    • recognize self-MHC molecules
    • those that interact with MHC molecules too strongly
  • function decreases with age (from puberty)


describe the cells located in the cortex vs medulla of the thymus

  • cortex = immature thymocytes
  • medulla = immunocompetent T cell (mature)


describe the 3 regions of the lymph nodes (secondary lymphoid organs)

  1. cortex
    • B cells mainly
    • primary follicle: un-activated lymphoid folicle
    • secondary follicle: activated
      • germinal centers = production of plasma and memory cells
  2. paracortex
    • T cells, dendritic cells (APCs)
    • activation of T cells
    • interaction of T and B cells
  3. Medulla
    • plasma cells secreting antibody and macrophages