BIOL 2420 Lecture Notes - Lecture 5: Natural Killer Cell, Protease, Vascular Permeability
26 Apr 2018
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Unit 4 – Lecture 5
NK Cells Kill Infected and Tumor Cells
Natural killer cells
- participates in the innate response against viral infections
- act more rapidly than other lymphocytes
o respond within hours of primary infection
- recognize virus-infected cells and induce them to commit suicide before they can replicate
o apoptosis
- complete elimination of the virus requires activated of a specific immune response
- can also attack tumour cells
- secrete multiple antiviral cytokines
o interferons
▪ named for their ability to interfere with viral replication
o interferon-alpha (IFN-) and interferon-beta (IFN-ß)
▪ target host cells and promote synthesis of antiviral proteins to prevent viral
replication
o interferon-gamma (IFN-)
▪ activates macrophages and other immune cells
Cytokines Create the Inflammatory Response
- inflammation is a hallmark reaction of innate immunity
- inflammation has three important roles in fighting infection in damaged tissue
1. attracting immune cells and chemical mediators to the site
2. producing a physical barrier to retard the spread of infection
3. promoting tissue repair once the infection is under control
o non-immunological function
- inflammatory response is created when activated tissue macrophages release cytokines
o cytokines attract other immune cells, increase capillary permeability, and cause
fever
- immune cells attracted to the site in turn release their own cytokines
Acute-Phase Proteins
- during the acute phase of infection the body responds by increasing the concentration of
various plasma proteins
o some of these proteins (produced mostly from the liver) are given the general name
of acute-phase proteins
▪ molecules that act as opsonins by coating pathogens
▪ antiprotease molecules that help prevent tissue damage
▪ C-reactive protein (CRP)
- Normally levels of these proteins decline to normal as the immune response proceeds
find more resources at oneclass.com
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Document Summary
Normally levels of these proteins decline to normal as the immune response proceeds: however, in chronic inflammatory diseases (like rheumatoid arthritis) elevated levels of acute-phase proteins may persist. Increased levels of crp are associated with increased risk of coronary heart disease: due to atherosclerosis as an inflammatory process that begins when macrophages in blood vessels ingest excess cholesterol and become foam cells. Elevated crp is not a specific indicator of atherosclerosis: crp levels can also be elevated in other actue and chronic inflammatory conditions. Found primarily in the granules of mast cells and basophils: active molecules that helps initiate the inflammatory response when mast cells degranulate, bring more leukocytes to the injury site to kill bacteria and remove cellular debris. Opens pores in capillaries: allows plasma proteins to escape into the interstitial space, causes local edema or swelling, dilates blood vessels (vasodilation) Increases blood flow to the area: result is hot, red, swollen area around a wound or infection site.
