Immunity Flashcards
What does the immune system do?
- protect against infection by pathogens-viruses,microbes including bacteria, fungi, and eukaryotic parasites
- isolate or remove foreign substances
- destroy cancer cells that arise in thebody
What are the different types of immune cells? There are 4.
- leukocytes (WBC)
- macrophages
- dendritic cells
- mast cells
What are Cytokines?
Messengers produced by a variety of individual cells, link the components of the immune system together. They are the chemical communication network that allows different immune system cells to talk to each other.
Cytokines:
IL-1
TNF
IL-6
Source-antigen presenting cells (marcophages)
Target Cells-talk to heper T cells, certiain brain cells, and systemic cells
Function-stimulate IL-2 receptor expression; induce fever, stimulate systemic responses to inflammation, infection, and injury
Cytokines:
IL-2
Source-most immune cells
Target Cells-helper T cells, T cells, NK cells, and B cells
Function–stimulate proliferation, promote conversation to plasma cells
Interferons (type I)
Source-most cell types
Target Cells-most cell types
Function–stimualte cells to produce antiviral proteins (innate response)
Interferons (type II)
source-NK cells and activated helper T cells
Target Cells-NK cells and macrophages
Function–stimulate proliferation and secretion of cytotoxic compouds
Chemokines:
What triggers them?
What do they trigger and what what do those triggered cells do?
Source-damaged cell, including endothelial cells
Target Cells-neutrophils and other leukocytes
Function–facilitate accumulation of leukocytes at sites of injury and inflammation
Colony-stimulating factors
Source-marcophages
Target Cells-bone marrow
Function–stimulate proliferation of neutorphils and monocytes
Innate Immune Response
- defenses at the body surfaces, the response to injury or infection known as inflammation, and family of antiviral proteins called interferons
- First Line of Defense: physical, mechanical, and biochemical barriers
What is the 2nd line of defense?
Inflammatory response
What happens in the Inflammatory Response, specifically during the vascular response?
- signs of inflammation
- vasodilation
- key to rest of the response-delivers other response materials and removes wastes from area
- plays important role in adaptive immunity (B and T lymphocytes) via use of lymphatics to clear area of debris
What. happens during the Inflammatory Response, specifically with the plasma protein response?
-complement: can cause direct destruction or activate other components
Complement system
consist of several plasma proteins that produce several factors that can destroy pathogens directly and can activate or collaborate with other components on the innate and adaptive immune responses.
Classical pathway
activated by proteins of the adaptive immune system (antibodies) bound to their specific targets (antigen)
What activates the Lectin pathway?
activated by mannose-containing bacterial carbohydrates
What activates the Alternative pathway?
activated by gram-negative bacterial and fungal cell wall polysaccharides
classical pathway route-antibody mediated initiated
signal is sent when bacteria is found and antibodies attach to the antigens on the bacteria:
chain: C1 > C4 > C2 > C3 which breaks up into C3a and C3b….C3 becomes C3b > C5 > C6 >C7 > C8 > C9. C5 becomes C5a. and C5b. C5b, C6, C7, C8, and C9 break off and form a channel into the bacteria which allows water and sodium to fluid in and lysis (kill) the bacteria.
C3a and C5a signal protease to enhance inflammation through chemotaxis
What makes up the membrane attack complex (MAC) which is a pentameric protein
C5b, C6, C7, and C8, and C9
come together and break off to make a MAC which allows extracellular fluid to go into bacteria and cause lysis
What is opsonin?
Extracellular proteins that bind to substances or cells that induce phagocytes to phagocytose the cell
-C3b is a great opsonin
What is the alternative pathway?
When C3b directly binds to the antigen on the bacteria instead of C1 and thus initiate lysis or opsonization.
What is the lectin pathway?
- bacteria has certain type of antigens, specifically a carbohydrate called Mannose. Mannose binding lectin protein will bind with mannose which initiates the lectin pathway. C4 loves mannose binding lectin protein
- C4 binds to Mannose binding lectin complex then C2, C3b, C5b, C6, C7, C8, and C9
What are kinins
polypeptides that cause vasodilation and smooth muscle contraction, nerve cell stimulation, and leukocyte chemotaxis
What are cytokines?
- soluble factors that are secreted by cells, contribute to resistance through specific receptor binding
- bind to receptors and promote activation proliferation and differentiation of immune cells
What are the different types of cytokines?
- interleukins
- tumor necrosis factors
- interferons
- colony stimulating factors
- transforming growth factors
What are interleukins?
- messengers produced by macrophages and luekoytes
- enhance adaptive immune reponse
- PRO inflammatory: IL-1 and IL-6
- ANTi inflammatory: IL-10 and tumore necrosis factor (TNF)
What are tumor necrosis factor alpha?
- secreted by macrophages and mast cells
- PRO inflammatory; local and systemic effects
- positive effect: induces fever and chemokine production
- negative effect: if prolonged can cause cachexia and shock
What are interferons?
- protect against viruses and modulate inflammation
- release by the cells infected by the virus
- antiviral proteins
What are mast cells and what to do they do?
- have vasoconstricting and vasodilating effects
- increase permeability
- release chemotactic factors (neutrophil and eosinophil factors)
- synthesize new mediators
-type of white blood cell that is found in connective tissues all through the body, especially under the skin, near blood vessels and lymph vessels, in nerves, and in the lungs and intestines
What is phagocytosis?
- occurs when phagocytes leave circulation and enter inflammation site
- opsonize > engulf > fuse > destroy target
Where are most plasma proteins made?
liver
What do lymphocytes mature in to?
T or B cells
What are T cells responsible for?
Help in cellular immunity by the activation of phagocytes, antigen sensitized cytotoxic T cells and release of cytokines and chemokines in response to an antigen
What are B cells responsible for?
humoral immunity aka antibody-mediated immunity
What is active (acquired) immunity?
- produced after exposure to an antigen or immunization
- long term
What is passive immunity
- no host immune system response
- temporary
Where are T cells synthesized?
-matures in thymus
Where do B cells come from and what does it do?
- mature in bone marrow
- has a B cell receptor which means it has an antibody on its plasma membrane to bind to an antigen
- express IgM
What do phagocytic cells do?
-process antigens, put them on the phagocytes’s surface where lymphocytes initiate the immune response against the specific antigen
Example of phagocytes
Dendritic cells, macrophages, B lymphocytes
What are helper T cells?
stimulates T cells, macrophages and B cells to make an immune response
-it is a type of WBC and a type of lymphocyte
Humoral Immune Response
- activated by B cells
- primary response: first exposure produces IgM and IgG
- secondary response: second exposure; the antibody produced is quicker and in larger amounts (esp. IgG)
Cellular Immune Response
- activated by T cells
- directly kill the antigen
- T memory cells also produced for secondary immune response
What are antibodies?
- protect host from infection through neutralization, agglutination, or precipitation
- antibody titers measure the level of circulating antibodies
- attenuated vaccines work via neutralization
- can be stimulated by presenting chemically inactivated antigens
- antibodies also function as opsonins, making antigen more likely to be phagocytized
What is the secretory immune response?
- systemic immune system
- plasma cells in secretory organs produce antibodies in secretions
- Immunoglobulins are secreted and act locally
- protect mucosal epithelia
Changes in immunity with aging?
- less T cell production
- B cells less responsive to new antigens
Characteristics of innate immune defense include
your skin and the inflammatory response
4 roles of the clotting cascade in inflammation
- prevention of infection
- limitation and control of inflammatory process
- Interaction with components of adaptive immune system to elicit a more specific response to contaminating pathogens
- preparation of the area of injury for healing through removal of bacterial products, dead cells, and other products of inflammation
What starts the phagocytosis?
-a foreign substance is introduced to the body, inflammation occurs, and then a phagocyte enters and begins phagoycytsosis
What are the intracellular organelles primarily responsible for phagocytosis?
- granulocytes (neutrophils, eosinoiphils, basophils)
- macrophages/monocytes
What type of cell injury results in death?
necrosis
What do basophils do?
- wbc/granulocyte
- important source of the cytokine IL 4 which regulates the adaptive immune response
What do monocytes do?
- largest normal blood cell
- produced in bone marrow, enter circulation, and migrate to the inflammatory site where they become macrophages
What do dendritic cells do?
-primary phagocyte located in the peripheral organs and skin where molecules released from infectious agents are encountered, recognized through PRR (pattern recognition receptors) < and internalized through phagocytosis
Interleukin 10
- ANTI-inflammatory
- produced from lymphocytes
- suppresses the growth of other lymphocytes and the production of proinflammatory cytokines by macrophages, leading to down regulation of both inflammation and the adaptive immune response
Interleukin 6
- PRO inflammatory
- come from macrophages, lymphocytes, fibroblasts, and other cells
- induce hepatocytes to produce many of the proteins needed for inflammation
Interleukin 1
- PRO inflammatory
- come from marcophages
- activates monocytes, other macrophages, and lymphocytes, thereby enhancing both innate and acquired immunity and act as a growth factor for many cells
What do natural killer T cells do?
recognize and eliminate cells infected with viruses, although they are also somewhat effective at elimination of other abnormal cells, specifically cancer cells
What are mast cells?
- most important cellular activator of inflammatory response
- are cellular bags of granules located in loose connective tissue close to blood vessels near the body’s outer surfaces
Chronic inflammation can be mediated by
an unsuccessful acute inflammatory response
Chronic inflammation can be mediated by
an unsuccessful acute inflammatory response
Chronic inflammation is associated with
a duration of 2 weeks or longer
What happens during Chronic inflammation?
an infiltration of lymphocytes and macrophages; if macrophages cannot limit tissue damage then the body forms a granuloma to isolate the infected area
What happens during acute inflammation
fever, leukocytes (increase WBCs), and plasma protein synthesis (which are mostly produced in liver)
what is a cytokine storm
A severe immune reaction in which the body releases too many cytokines into the blood too quickly
-can lead to multi organ failure
what is a cytokine storm
- A severe immune reaction in which the body releases too many cytokines into the blood too quickly
- can lead to multi organ failure
Stages of Inflammatory Response
- vasodilation
- increased vascular permeability which causes redness and edema
- WBC adheres to inner walls of vessels
Stages of Inflammatory Response
- vasodilation
- increased vascular permeability which causes redness and edema
- WBC adheres to inner walls of vessels
What it the purpose of the complement cascade?
produces several factors that can destroy pathogens directly and can activate or collaborate with other components of the innate and adaptive immune reponses.
