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108 Cards in this Set
- Front
- Back
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Which type of immunity can one survive without?
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Adaptive
-Cannot survive without innate immunity however! |
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Is innate immunity ever not on?
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no
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What is the timeframe for an innate immune reaction?
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Within 0-12 hours of infection
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What is the purpose of the innate immune system?
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To prevent infection or eliminate a particle/infectious agent
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Is innate immunity completely separate from adaptive immunity?
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No - some effector mechanisms of innate immunity help to eliminate organisms/pathogens in adaptive responses
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How does innate immunity mesh with adaptive immunity?
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It stimulates and influences the adaptive immune response to optimize its effect
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What are the 3 functions of epithelia in innate immunity?
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1. Physical barrier to infection
2. Kill microbes by locally produced antibiotics 3. Kill microbes/infected cells by intraepithelial lymphocytes |
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4 epithelial barriers in the body:
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1. skin
2. gut 3. lungs 4. eyes/nose |
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What is the mechanical mechanism that allows epithelium to resist infection in all barriers?
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Tight junctions that join the epithelial cells
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Which epithelial barriers have longitudinal flow of air/fluid?
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Skin and Gut
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Which epithelial barrier has movement of mucus by cilia?
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lungs
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What epithelial barriers have chemical mechanisms consisting of antibacterial peptides?
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-Skin
-Gut -Lungs |
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Where are fatty acids an effective chemical mediator of immunity?
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On the skin
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Where are low pH and enzymes an effective chemical mediator of immunity?
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In the gut
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Where are salivary enzymes like lysozyme chemical agents of immunity?
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In the eyes/nose
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Where are normal flora found as a microbiological mechanism of immunity?
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In the skin and gut
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How does normal flora on the skin act as an immune barrier?
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Microbiota compete with pathogens for nutrients and colonization sites
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What is the environment of the skin like chemically?
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Dry and acidic
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What are 3 chemical factors found on the skin that act immunologically?
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-Fatty acids
-Lysozyme -Immunoglobulins |
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What special cells act to prevent infection at the skin?
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Intrinsic immune sentinels
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SALT
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Skin associated lymphatic tissue
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What are 2 types of intrinsic immune sentinels?
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-Resident langerhans cells (dendritic cells)
-Intraepidermal lymphocytes |
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How many bacteria make up the normal commensal microbiota of the GI tract?
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10^14
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List the 5 mechanisms of innate immunity at Mucosal surfaces (resp, GI, and UG):
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1. Anatomic barriers
2. Physiologic barriers 3. Commensal microbiota 4. Secretory antibodies 5. Intrinsic immune sentinels |
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What is the mucosal antibody?
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IgA
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What is the function of secreted IgA?
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To prevent bacterial adherence to mucosal epithelial surfaces.
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Where is IgA transported into the gut lumen?
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Through epithelial cells at the base of crypts
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What is the cellular response of innate immunity called?
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Inflammation
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What are the 3 main components of an inflammatory reaction?
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1. Recruitment of wbcs
2. Activation of WBCs 3. Elimination of the pathogen |
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What are 4 means of pathogen elimination by innate immunity?
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1. Macrophage eating
2. Complement activation 3. Neutrophil eating/respiratory burst 4. Solule mediators - eicosanoids, NO, and ROS |
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List the 4 main players in inflammatory reactions:
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1. Cytokines
2. Complement 3. Neutrophils 4. Soluble Mediators |
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What causes rubor and calor during inflammation?
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Vasodilation
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What causes tumor?
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Increased vascular permeability - exudate
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What causes dolor (pain)?
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Damage to tissue and phagocyte influx
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What are the phagocytes that act during inflammatory response?
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-Neutrophils
-Macrophages (resident to the skin or mucosal surface) |
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What are the 3 steps in the functional response of phagocytes during inflammation?
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1. Recruitment to site
2. Recognition of microbes 3. Phagocytosis |
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What is Phagocyte Recruitment?
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Protein:protein interactions between traveling WBCs and the blood vessels
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What proteins are on WBC surfaces that allow it to bind to ECs on blood vessels?
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-Integrin (low affinity)
-Selectin ligands |
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What is responsible for rolling of WBCs on ECs?
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Sialyl glycoproteins binding to e-Selectin and p-selectins on ECs
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What has to happen to EC's in order for rolling of WBCs??
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Cytokine release from macrophages that ate microbes; it activates ECs to increase their E-selectin expression
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What are the macrophage produced cytokines that increase selectins on ECs?
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-TNF
-IL-1 |
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What molecules are responsible for pavementing and stable adhesion of WBCs to ECs?
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Integrin binding
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What increases the integrin to high affinity state on WBCs?
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Chemokines
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What is the final step in recruitment after pavementing?
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Diapedesis
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Once WBCs get into the interstitial space, what is their job next?
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To recognize the microbial targets
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What feature of WBCs allows them to recognize the microbial targets?
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PRRs
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PRR:
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Pattern recognition receptor
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Are there PRRs on host cells?
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no
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Can PRRs undergo somatic hypermutation?
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No; they are encoded in germline DNA.
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What is the source of dsRNA as a pattern for WBC microbial recognition?
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Replicating viruses
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What is the principal receptor for dsRNA? Response?
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-TLR3
-Causes Type I IFN production |
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What is the source of LPS as a pattern for WBC microbial recognition?
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Gram negative bacteria
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What is the principal receptor for LPS? Response?
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Receptor: LBP and TLR4
Response: Macrophage activation |
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What is the source of Flagella as a pattern for WBC microbial recognition?
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Bacteria and protozoa
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What is the principal receptor for Flagella? Response?
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-TLR5
Response: macrophage activation and cytokine production |
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What is the source of Unmethylated CpG DNA as a pattern for WBC microbial recognition?
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Bacterial DNA
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What is the principal receptor for Unmethylated CpG DNA? Response?
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TLR9
Response: macrophage activation |
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What is the source of N-formyl peptides as a pattern for WBC microbial recognition?
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Bacterial protein
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What is the principal receptor for N-formyl peptides? Response?
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fMLP
Response: neutrophil and macrophage activation |
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What is the source of mannose as a pattern for WBC microbial recognition?
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Surface glycans on bacteria
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What is the principal receptor on WBCs for mannose? Response?
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-Mannose receptor
-Mannose Binding lectin Response: phagocytosis and opsonization |
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What is the source of phosphorylcholine as a pattern for WBC microbial recognition?
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Microbial cell membranes
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What is the principal receptor for Phosphorylcholine? Response?
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C-reactive protein
Response: opsonization and complement activation! |
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Once the wbc's recognize microbes via their PRRs, what needs to happen?
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Phagocytosis
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3 types of microbicidal molecules used during phagocytosis:
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1. Lysosomal enzymes
2. ROIs 3. NO |
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What is the enzyme that phagocytes use to make Nitric oxide?
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Inducible nitric oxide synthase
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What is the precursor of nitric oxide?
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Arginine
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What is the enzyme used to make ROIs?
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NADPH oxidase
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In what organelle does killing by lysosomal enzymes occur?
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Phagolysosomes
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Why is overproduction of ROIs and NO harmful?
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Because they can cross the cell membrane and kill extracellular microbes and host tissues.
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When Macrophages eat bacteria, what 2 processes result?
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1. Loading of antigen onto Class II MHC and presentation to Th cells
2. Production of chemical mediators |
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List 4 mediators released by activated macrophages:
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1. Cytokines
2. Chemokines 3. Nitric oxide 4. Lipid mediators |
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What is the first WBC to emigrate during inflammation?
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Neutrophils
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3 special chemical mediators made by neutrophils:
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-Defensins
-Lysozyme -Lactoferrin |
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What is the principal event that allows neutrophils to kill ingested bacteria?
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Respiratory burst
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Which enzyme is essential for the respiratory burst?
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Phox - phagocyte oxidase
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In what disease is phox activity deficient?
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Chronic granulomatous disease
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What inheritance pattern is seen in the majority of CGD cases?
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X-linked
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What is the prominent clinical feature of CGD?
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Recurrent pyogenic bacterial infections
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2 diagnostic features of CGD:
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-Neutrophilia
-NBT dye reduction - no change |
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What do eosinophil granules contain?
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-Heparin
-Hydrolytic enzymes -Major basic protein |
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What do basophil granules contain?
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Histamine
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What do mast cell granules contain?
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Heparin and histamine
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Which cells are important in allergic responses?
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Basophils and mast cells
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Which granulocytes are capable of phagocytosis?
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-Neutrophils
-Eosinophils |
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Are basophils phagocytic?
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no
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What cells are the progenitor of dendritic cells?
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The same cell that makes monocytes and macrophages
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What type of receptors are on dendritic cells?
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The same PRRs as on macrophages and neutrophils
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What is TLR
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a PRR
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What is the maturation of dendritic cells like?
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-Born in bone marrow
-Migrate to reside in tissues -Ingest microbes/particles via macropinocytosis (immature) -Migrate to present ingested Ag to T lymphs in periph lymphoid tissues (mature) |
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So what is the main difference between dendritic cells and macrophages?
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-Dendritic cells leave tissues to present Ag to lymphocytes
-Macrophages stay in tissue at infection site to eliminate the pathogen there. |
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What type of cell are Natural Killer cells?
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Lymphocytes - large and granular
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How are NK cells different from T and B lymphocytes?
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They lack TCR or BCR
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What CD is TCR?
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CD3
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What activates NK cells?
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Nothing; they're active without prior Ag exposure or presentation
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What 2 types of cells are NK cells specialized to kill?
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-Virus infected cells
-Tumor cells |
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What 2 cytotoxins do NK cells secrete?
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-Perforin
-Granzyme |
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What is the ultimate result of NK cytokine secretion?
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Apoptosis of virus/tumor cells via Fas-FasL interactions.
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2 Ways by which NK cells kill:
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1. Direct
2. Indirect |
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What is the direct method of NK killing infected cells?
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ADCC - antibody dependent cellular cytotoxicity
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What happens in ADCC?
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A virus-infected cell is bound by IgG, which triggers the NK cell to kill the infected cell.
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What is the indirect method of NK cytotoxicity?
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A macrophage with ingested microbe secretes Il-12 which activates the NK cell to produce IFN-y, which activates the macrophage so it can kill the microbes it ate.
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3 mediators that are capable of activating NK cells:
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-IL-12
-IFN-a -IFN-B |
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What does IFN-y secreted by NK cells do?
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-Activates TH1 type T cells
-Activates macrophages |
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What are the receptors that normal NK cells express?
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-Activating receptor
-Inhibitory recepto |
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What is the ligand for NK cell's
-Activating receptor -Inhibitory receptor |
Activtng: a ligand on normal autologous cells
Inhibiting: Self class I MHC with self peptide on it |
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What happens when NK cells engage with the ligands on normal self cells?
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Nothing; the NK cell is not activated.
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What happens when NK cells engage with the ligands on virus infected cells?
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Virus infected cells lack Class I MHC and so the NK cell missing the inhibitory signal is activated and kills the infected cell.
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