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48 Cards in this Set
- Front
- Back
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Name 3 protective mechanisms that the INNATE system uses.
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Barriers
Humoral Factors Phagocytic Cells |
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Why can't pathogens survive on the skin?
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1. Surface is dead and lacking nutrients
2. Acids in sweat and sebum 3. Commensal bacteria out-compete pathogens for nutrients |
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What are vulnerable areas (eyes, nasal passages) protected by with the INNATE system?
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The bacteriocidal agent LYSOZYME, which digests bacterial walls
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Name two phagocytic cells.
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Neutrophils and Monocytes
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What is a Pattern Recognition Receptor (PRR)?
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On phagocytic cells, sense "dangerous" molecules and trigger phagocytosis.
Note: The Toll-like receptors are a major family |
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Opsonization
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Promotion of phagocytosis
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An immature macrophage is called what?
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Monocyte
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When does adaptive immunity come into play?
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When the innate mechanisms have FAILED (aw, sad..)
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How do the adaptive and innate systems work together?
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Adaptive immunity improves and optimizes the efficiency of innate mechanisms, like complement, phagocytosis, etc.
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Antigen
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Foreign substances that stimulate an immune response
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Dendritic cells are responsible for what?
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Initial recognition of antigen via innate receptors
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Where do T cells and B cells develop?
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B cells - Bone Marrow
T cells - Thymus |
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What do B cells develop into?
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Plasma cells, which secrete the antibodys
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What are the two types of T cells?
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CD4 - T Helper Cells
CD8 - Cytotoxic Killer Cells |
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Do Natural Killer cells express antibody or t-cell receptors?
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Nope! They display surface receptors for antibodies and non-specific receptors. They are a part of the innate system and kill non-specifically.
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How many receptors can a B or T cell express?
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Thousands, but only of one specificity
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Which MHC classes go with which T cell type?
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CD4 Helper - MHC 2
CD8 Killer - MHC 1 |
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What does the MHC do?
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Presents antigen to the T cell receptor
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What is the main type of antibody?
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IgG, but IgM are the first to appear
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Class switch is controlled by what?
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T cells determine B cell differentiation
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Where do B cells mature into plasma cells?
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Bone marrow, splenic red pulp and lymph node medulla
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What is the bodys first response to an antigen called?
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Priming, and it includes a latent period of 7-10 days before antibody is detected
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What is the complement system made up of?
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More than 20 soluble complex proenzymes that are part of a cascade group
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What are the two complement pathway types?
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Alternative and Classical
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Where is C3 made?
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Made in the liver, but split in the blood
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What is the main feature of the alternative pathway?
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The absence of antibody. It instead is activated by bacteria, yeats and fungi
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Which Factors in the plasma work to inactivate C3b?
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Factors H and I
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What are the main effects of the Alternative Pathway? (2)
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1. To coat bacteria with iC3b to become major targets for phagocytes
2. To induce an acute inflammatory response via C3a and C5a |
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What are two triggers of the Classical Pathway of complement?
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The binding of antibody to antigen or binding of soluble lectins (collectins) to pathogens
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What complex does the classical pathway eventually produce, which can digest C3?
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C4b2b enzyme
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What is special about the "a" fragments of complement?
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They are chemotactic for neutrophils and inducers of acute inflammation. Also called anaphylotoxins
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What is MAC?
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Membrane Attack Complex. This is the lytic pathway of complement function and is initiated via enzymes C3bBb3b or C4b2b3b.
Results in pore formation and cell lysis by osmotic shock. |
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What inhibits complement?
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Factors H and I and Delay Accelerating Factor (DAF - only in classical)
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What cells are MHC1 expressed on?
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All except neurons and red blood cells
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What is the function of MHC1 molecules?
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To bind antigenic peptides derived from WITHIN the cell (i.e. virus!)
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Which cells express MHC2?
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Macrophages, dendritic cells and B cells
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Does MHC1 or 2 interact with larger peptides?
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MHC 2! Has a larger groove so interacts with peptides around 20 amino acids long, vs. the 8-10 that MHC1 can
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What is the function of MHC2?
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Interacts with CD4 T cells and presents antigenic peptides from an EXTRACELLULAR source (i.e. bacteria)
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What is the function of CD4 T cells?
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To regulate all aspects of both immune and innate response. Also secrete cytokines that influence many cell aspects.
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Which are the most prominent lymphocytes in the blood?
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CD4 - 50%
CD8 only 20% |
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What is the function of CD8 T cells?
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To kill virus-infected cells
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How many signals are required for a T cell to be activated?
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2 - interaction of TcR with antigen and also interaction of T molecule CD28 with ligand on antigen presenting cell, CD80. This second signal only occurs after recognition of DANGER.
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What happens if a T cell receives signal 1, but not 2?
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It does into apoptosis as a control
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If both signals (antigen and 'danger') are received by a T cell, what happens?
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Cell is activated into clonal expansion and produces cytokines
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What determines if a CD4 cell diffentiates into a TH1 or TH2?
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TH1 if macrophages are the APC and TH2 if B cells are the APC
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What is the role of IL-4?
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Stimulates B cell growth and heavy chain switch
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What are the roles of IL-5 and IL-6?
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Activate B cells and stimulate proliferation
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What is the differentiation of TH0 caused by?
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Cytokines secreted by APCs - macrophages produce IL-12 and B cells produce IL-10
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