5-2
T/F Type I interferons block viral replication in infected host cells primarily by triggering the production of antiviral proteins that degrade both viral mRNA and host cell mRNA.
Tru tru
Name the two cytokines that are most important in stimulating acute inflammation.
Tumor necrosis factor-alpha (TNF-α) and Interleukin-1 (IL-1)
Describe specifically how type I interferons are able to block viral replication within an infected host cell.
Type I interferons, produced by virtually any virus-infected cell, provides an early innate immune response against viruses. Interferons induce uninfected cells to produce enzymes capable of degrading mRNA. These enzymes remain inactive until the uninfected cell becomes infected with a virus. At this point, the enzymes are activated and begin to degrade both viral and cellular mRNA. This not only blocks viral protein synthesis, it also eventually kills the infected cell.
Resting phagocytes are activated by inflammatory mediators such as bacterial products, complement proteins, and proinflammatory cytokines. As a result, the phagocytes produce endocytic pattern-recognition receptors that recognize and bind to pathogen-associated molecular patterns found in many microorganisms. They also exhibit increased metabolic and microbicidal activity.
activation
A multiprotein complex that forms in macrophages as a result of PAMPs and DAMPs binding to their respective PRRs and DRRs that leads to an inflammatory response and the production of inflammatory cytokines is called what?
an inflammasome
Cytokines that promote inflammation by enabling white blood cells to adhere to the inner surface of blood vessels, migrate out of the blood vessels into the tissue, and be chemotactically attracted to the injured or infected site.
chemokines
The movement of phagocytes toward an increasing concentration of some attractant such as bacterial factors, complement components, chemokines, and phospholipids released by injured host cells.
chemotaxis
Movement of phagocytes toward an increasing concentration of some attractant such as PAMPs, C5a, chemokines, fibrin split products, kinins, and DAMPs best describes what step in phagocytosis?
chemotaxis of phagocytes
A wide variety of intercellular regulatory proteins produced by many different cells in the body that ultimately control every aspect of body defense. Cytokines activate and deactivate phagocytes and immune defense cells, increase or decrease the functions of the different immune defense cells, and promote or inhibit a variety of nonspecific body defenses.
cytokines
Phagocytes contain membranous sacs called lysosomes that contain various digestive enzymes and microbicidal chemicals. The lysosomes fuse with the phagosomes containing the ingested microbes and the microbes are destroyed.
destruction
By blocking the acidification of the phagosome, some bacteria are better able to resist what step in phagocytosis?
destruction by lysosomes
Lysosomes fusing with phagosomes is the mechanism behind what step in phagocytosis?
destruction of microbes by phagocytes
The attachment of microbes to phagocytes by way of an antibody molecule called IgG or the complement proteins C3b and C4b produced during the complement pathways.
enhanced attachment
Defense molecules such as IgG, C3b, C4b, CRP, and MBL are involved in what step in phagocytosis?
enhanced attachment or opsonization by phagocytes
enables phagocytes to leave the blood and enter the tissue at infected and injured site
inflammation
Signaling PRRs found on cell surfaces tend to stimulate the synthesis of what?
inflammatory cytokines
Following attachment, polymerization and then depolymerization of actin filaments send pseudopods out to engulf the microbe and place it in an endocytic vesicle called a phagosome. During this process, an electron pump brings protons (H+) into the phagosome. This lowers the pH within the phagosome so that when a lysosome fuses with the phagosome, the pH is correct for the acid hydrolases in the lysosome to effectively function and break down cellular proteins.
ingestion
Polymerization and then depolymerization of actin filaments send pseudopods out to engulf microbes and place them in phagosomes best describes what step in phagocytosis?
ingestion of microbes by phagocytes
Cytokines that prevent viral replication within infected cells and activate a variety of cells important in immune defenses.
interferons
Contain phagocytes that remove microorganisms from the lymph.
lymph nodes
Contain phagocytes that remove microorganisms that enter the mucous membranes and the skin.
lymph nodules
Unencapsulated masses of lymphoid tissue containing fixed macrophages and ever changing populations of B-lymphocytes and T-lymphocytes and located in the respiratory and gastrointestinal tracts describes what?
lymph nodules
Oxygen-independent killing systems
lysosomes containing beta-defensins, lysozyme, lactoferrin, cathepsin G, elastase, bactericidal permeability increasing protein, other digestive enzymes
Danger-associated molecular patterns (DAMPs)
molecules displayed on stressed, injured, infected, or transformed human cells that can also be recognized as a part of innate immunity. Examples include altered membrane phospholipids and heat shock proteins.
signaling pattern recognition receptors
once they bind pathogen-associated molecular patterns, promote the synthesis and secretion of intracellular regulatory molecules such as the cytokines, chemokines, and interferons that are crucial to initiating innate immunity and adaptive immunity.
endocytic pattern-recognition receptors
pattern-recognition receptors found on the surface of phagocytes that promote the attachment of microorganisms to phagocytes and their subsequent engulfment and destruction.
"Cytokines are pleiotropic, redundant, and multifunctional"
pleiotropic - a particular cytokine can act on a number of different types of cells rather than a single cell type. redundant - a number of different cytokines are able to carry out the same function. multifunctional - the same cytokine is able toregulate a number of different functions.
Oxygen-dependent killing system
reactive oxygen species(ROS) oxidize most of the chemical groups found in protein, enzymes, carbohydrates, DNA and lipids Ex: superoxide anion, hydrogen peroxide...
Danger recognition receptors
receptors in the cytosol of various body defense cells that recognize danger-associated molecular patterns.
Pattern Recognition Receptors (PRRs)
receptors on the surface of various body defense cells that recognize pathogen-associated molecular patterns.
These receptors promotes the synthesis and secretion of intracellular regulatory molecules such as cytokines.
signaling PRRs
Blood carries microorganisms to ___________ where antigens are exposed to ever-changing populations of circulating to B-lymphocytes and T-lymphocytes.
spleen
Contains phagocytes that remove microorganisms from the blood.
spleen
Describe how an overactive TLR-4 receptor can increase the risk of SIRS in a person if Gram-negative bacteria enter the bloodstream.
-People born with overactive PRRs or deficient PRR immune signaling pathways are at increased risk of inflammatory damage by lower numbers of specific pathogens. -People with overactive TLR-4 receptors may be more prone to developing SIRS from gram-negative bacteria.
Briefly describe two specific examples of how an improper functioning PRR can lead to an increased risk of a specific infection or disease.
-People with chronic sinusitis that does not respond well to treatment have decreased activity of TLR-9 and produce reduced levels of human beta-defensin 2 and mannan-binding protein needed to initiate the lectin complement pathway. -Mutations in the gene coding for NOD2 that prevent the NOD2 from recognizing muramyl dipeptide make a person more susceptible to Crohns disease, an inflammatory disease of the large intestines.
2 endocytic PRRs
1. Mannose receptors 2. Scavenger receptors 3. Opsonin receptors
Inflammasome
A multiprotein complex that forms in macrophages as a result of PAMPs and DAMPs binding to their respective PRRs an DRRs that leads to an inflammatory response and the production of inflammatory cytokines.
Briefly describe the role of autophagy in removing intracellular microbes.
A process that engulfs intracellular microbes and delivers them to lysosomes for degradation.
Cytokines
A wide variety of intercellular regulatory proteins produced by many different cells in the body that ultimately control every aspect of body defense. Cytokines activate and deactivate phagocytes and immune defense cells, increase or decrease the functions of the different immune defense cells, and promote or inhibit a variety of nonspecific body defenses.
Circulating phagocytes produce surface receptors that enabling them to squeeze out of the capillary and be attracted to the site of infection, produce PRRs, and increase metabolic and microbicidal activity. This best describes what step in phagocytosis?
Activation of phagocytes
Interferons
Cytokines that prevent viral replication within infected cells and activate a variety of cells important in immune defenses.
Chemokines
Cytokines that promote inflammation by enabling white blood cells to adhere to the inner surface of blood vessels, migrate out of the blood vessels into the tissue, and be chemotactically attracted to the injured or infected site.
Molecules displayed on stressed, injured, infected, or transformed human cells that can also be recognized as a part of innate immunity. Examples include altered membrane phospholipids and heat shock proteins.
DAMPs
Found on the surface of phagocytes, these receptors promote the attachment of microorganisms to phagocytes.
Endocytic pattern-recognition receptors
Most tissue destruction associated with bacterial infections is a result of what?
Extracellular killing by phagocytes
Describe what causes most of the tissue destruction seen during microbial infections
Extracellular killing by phagocytes.
T/F Specific cytokines are typically produced by a specific type of cell in the body, interact with a specific type of cell, and carry out a specific function.
False
State what happens when either phagocytes are overwhelmed with microbes or they adhere to cells to large to be phagocytosed.
If the phagocyte is overwhelmed with microorganisms, the phagocyte will empty the contents of its lysosomes by a process called degranulation in order to kill the microorganisms or cell extracellularly. These released lysosomal contents, however, also kill surrounding host cells and tissue.
TNF-alpha, IL-1, and chemokines are examples of cytokines that promote what?
Inflammation
Pyroptosis
Inflammatory response-induced cell suicide. Pyroptosis
Tissue fluid picks up microbes, enters the lymph vessels as lymph, and then enters _________________ where antigens are exposed ever-changing populations of circulating to B-lymphocytes and T-lymphocytes.
Lymph nodes
People that lack the enzyme oxidase in the cytoplasmic membrane of their phagocytes due to a genetic disorder are more susceptible to infection. Why might this be?
their phagocytes cannot produce defensins and acid hydrolases (proteases) that kill microbes
2 signaling PRRs found on the host cell cytoplasm.
NODS such as NOD-1 and NOD-2 and CARD-containing proteins such as RIG-1 and MDA-5
Describe the major difference between the effect of the cytokines produced in response to PAMPs that bind to cell surface signaling PRRs and endosomal PRRs.
PAMPs that bind to cell surface PRRs stimulate the synthesis of cytokines such as IL-1, TNF-alpha, and IL-8 that promote an inflammatory response in order to send defense cells and defense chemicals in the blood to the infected site. PAMPs that bind to endosomal PRRs stimulate the synthesis of cytokines called interferons that block viral replication within infected host cells.
Cytokines that block viral replication and kill infected host cells are known as what?
type 1 interferons
Signaling PRRs found in the membranes of the endosomes (phagolysosomes) tend to stimulate the synthesis of what?
type-1 interferons
A general recognition of pathogen-associated molecular patterns by means of endocytic pattern-recognition receptors on the surface of the phagocytes. Unenhanced attachment
unenhanced attachment
Bacterial capsules best help bacteria block what step in phagocytosis?
unenhanced attachment
2 signaling PRRs found in the endosomes of phagocytic cells.
TLR-3 and TLR-7
2 signaling PRRs found on host cell surfaces
TLR-4 and TLR-5