Unit II Flashcards
What is aplastic anemia?
Normocytic-normochromic anemia that results from a loss of blood cell precursors, causing hypoplasia of bone marrow, RBCs, WBCs, and platelets.
What are the four classic signs of inflammation?
calor (heat), rubor (redness), tumor (swelling), and dolor (pain)
What is the innate immune system?
nonspecific defense mechanism, immediately or very soon (minutes to hours) Includes physical barriers: skin, mediators in the blood, immune system cells
What is the adaptive immune system?
antigen-specific response. More complex than innate. Requires antigen processing. Involves creating cells specifically designed for that antigen. Also includes memory for faster future encounters
Signs of acute inflammation
rapid in onset and of short duration, lasting from a few minutes to as long as a few days, and is characterized by fluid and plasma protein exudation and a predominantly neutrophilic leukocyte accumulation.
What are the cellular infiltrates for acute inflammation?
neutrophils
Signs of Chronic inflammation
more insidious, is of longer duration (days to years), and is typified by influx of lymphocytes and macrophages with associated vascular proliferation and fibrosis (scarring).
What are the cellular infiltrates for chronic inflammation?
lymphocytes and macrophages
What are the agents that cause acute inflammation?
Infection, trauma, tissue necrosis, foreign material, and immune reactions
What is the roll of toll like receptors?
Pattern recognition receptors found on the surface and within the host cell that can detect foreign material. Once activated it triggers the production of transcription factors to create proteins that mediate inflammation, interfere with action of infectious agents (interferons) and promote lymphocyte activation.
What is an inflammasome?
receptors that stimulate inflammation via activation of caspase-1. Caspase-1 forms active Interleukin-1β (IL-1β), which then recruits leukocytes that come
in to clean up dead cells
**recognizes products of dead cells like ATP and free floating DNA
inflammasome induce the secretion of what molecule?
Interleukin-1β
What are exudates?
An exudate is formed in inflammation because vascular permeability increases as a result of the increase in interendothelial spaces.
**typical inflammation response
What are transudates?
A transudate is formed when fluid leaks out because of increased hydrostatic pressure or decreased osmotic pressure.
**noninflammatory conditions/ vascular wall still in tact
What are the two major changes during acute inflammation?
increased blood flow and increase vessel permeability
What mechanism contribute to increase vessel permeability?
Endothelial cell contraction leading to intercellular gaps in postcapillary venules
Injury of endothelial cells –> incomplete endothelial layer
Transcytosis
quick response endothelial contraction is stimulated by what molecules?
histamines
Longer-term contraction is prompted by what molecules?
Cytokines like IL-1 and TNF
What is fibrosis?
If the tissue cannot regenerate or if there has been significant tissue destruction then
instead connective tissue fills the void
What adhesion molecules grab onto sugars that are present on the surface of leukocytes to promote leukocyte rolling?
P and E selectins
What molecule stimulates P-selectins?
histamine
What molecule stimulates E-selectins?
IL-1
What is stasis?
caused when numerous dilated small vessels become packed with red blood cells and blood viscosity increases
What is a low concentrations of protein and few or no blood cells in the extravascular space indicative of?
transudates
explain the adhesion process for leukocytes
When the adherent leukocytes encounter the displayed chemokines, the cells are activated, and their integrins undergo conformational changes and cluster together, thus converting to a high-affinity form
explain the adhesion process of endothelial cells
cytokines, notably TNF and IL-1 (also secreted at sites of infection and injury), activate endothelial cells to increase their expression of ligands for integrins. These ligands include intercellular adhesion molecule-1 (ICAM-1),
Where does diapedesis take place?
mainly in the venules of the systemic vasculature
what are opsonins?
Host proteins that coat microbes and target them for phagocytosis
Name examples of opsonins
IgG, compliment system (C3b), collectins
What are neutrophil extracellular traps?
tracellular fibrillar networks that are produced by neutrophils to prevent the spread of microbes.
Essentially they release their own chromatin to trap these microbes in place.
What collateral tissue damage is associated with inflammation?
- Tissue surrounding infectious agents may become damaged.
- Cleaning up necrotic tissue by the inflammatory process may cause additional damage
- Inflammatory process is directed against host tissues (i.e. autoimmune diseases)
What are common causes for defective leukocyte function?
- aplastic anemia secondary to chemotherapy
- Diabetes
- Chédiak-Higashi syndrome which has mutations in the proteins responsible for trafficking of
organelles; thus phagosomes and lysosomes cannot properly fuse.
What are the trademark cells for chronic inflammation?
monocytic cells - lymphocytes, macrophages, dendritic cells, plasma cells
What are the characteristics of chronic inflammation?
- inflammation with mononuclear cells
- tissue destruction
- repair
Describe a smear with acute inflammation of the lung
neutrophils filled in the alveolar space and blood vessel congestion
what is pruritus?
severe itching the skin
What are macrophages in the liver called?
Kupffer cells
What induces classical macrophage activation?
microbial products such as endotoxin, by T cell–derived signals, importantly the cytokine IFN-γ
What do classically activate macrophages produce?
NO, and ROS, all of which enhance their ability to kill ingested organisms, and secrete cytokines that stimulate inflammation
What induces alternative macrophage activation?
cytokines other than IFN-γ, such as IL-4 and IL-13, produced by T lymphocytes and other cells, including mast cells and eosinophils
What do alternative activated macrophages produce?
growth factors that promote angiogenesis, activate fibroblasts and stimulate collagen synthesis.
What is the principal role for alternative activated macrophages?
tissue repair, fibrosis, anti-inflammatory effects
What do TH1 CD4+ T lymphocytes secrete?
IFN-ɣ which activates classical pathway macrophages
What do TH2 CD4+ T lymphocytes secrete?
IL-4, IL-5, IL-13 which activates alternative pathway macrophages; also activates eosinophils
What do TH17 CD4+ T lymphocytes secrete? I
L-17 which recruits neutrophils and monocytes
Which chemokine recruits eosinophils?
eotaxins
What type of antibody is found on mast cells?
IGE
What cells are central players in allergic reactions, including anaphylactic shock?
IgE armed mast cells
What is the characteristic of granulomatous inflammation?
aggregates of activated enlarged macrophages with scattered lymphocytes
What is the prototype of a granulomatous disease?
tuberculosis
What are diseases associated with Granulomatous inflammation?
Crohn’s disease and sarcoidosis
what are the cells of chronic inflammation?
Macrophages
Lymphocytes
Eosinophils
Mast cells
What are the cytokines associated with acute phase reaction aka systemic inflammation?
TNF, IL-1, and IL-6 are responsible for many of the systemic effects
what cells produces the cytokines associated with acute phase reaction?
leukocytes
What triggers a fever?
a response to substances called pyrogens that act by stimulating prostaglandin synthesis in the vascular and perivascular cells of the hypothalamus.
what is the role of IL-6 in acute phase reactions?
IL-6 stimulates the hepatic synthesis of a number of plasma proteins
What are the acute phase proteins?
C-reactive protein (CRP) and serum amyloid A (SAA) protein are known to adhere to cell walls and may act as opsonins
What is used to test for the presence of inflammation?
erythrocyte sedimentation rate (ESR)
Fibrinogen binds red blood cells causing them to form stacks that quickly form sediments
What cytokine cause an increased number of immature white blood cells (early release)?
TNF and IL-1
What infection is assocaited to neutrophilia?
Bacterial infection
What infection is associated with lymphocytosis?
viral infection
What infection is associated with eosinophilia?
asthma and parasitic infection
What infection is associated with leukopenia?
specific infection like typhoid fever
What triggers the production of leukocytes?
colony stimulating factor
What are the two vasoactive amines and where are they stored?
histamine and serotinin both stored in mast cells
What is the role of histamine?
arterial dilation and & endothelial contraction
What is the role of serotonin?
vasoconstriction to aid in clotting
Where is serotonin found?
in platelet granules that are released during platelet aggregations
What stimuli cause mast cells to release histamine?
Physical features - trauma or heat Immune – Binding of IgE Compliment (C3a, C5a) Histamine releasing proteins (from leukocytes) Neuropeptides Cytokines (IL-1, IL-8)
name of the source of arachidonic acid metabolites
Leukocytes, mast cells, endothelium & platelets
how are AA metabolites inactivated?
by spontaneous decay and enzymes
What are the two major pathways of arachidonic acid metabolism?
cyclooxygenase and lipoxygenase pathway
The cyclooxygenase pathway leads to what products?
prostaglandins and thromboxanes
What is the role of prostaglandins?
causes vasodilation and inhibits platelet aggregation
What is the role of thromboxanes?
causes vasoconstriction and promotes platelet aggregation
The lipoxygenase pathway leads to what products?
leukotrienes and lipoxins
What is the role of leukotrienes?
causes bronchoconstriction and increased vascular permeability
What is the role of lipoxins?
inhibit neutrophil chemotaxis and adhesion to endothelium and thus serve as endogenous **antagonist of leukotrienes.
What medication would you use to block the cyclooxygenase pathway?
NSAIDs
What medication would you use to block the entire arachidonic acid metabolites?
glucocorticoid steroids
What enzyme does glucocorticoid sterioids inhibit?
phospholipase
**stops the release of all AA metabolites
What cell derived mediator contributes to pain and fever?
prostaglandins
What is platelet activating factor?
phospholipid-derived mediator with a broad spectrum of inflammatory effects.
Effects include: platelet aggregation, vasodilation, vascular permeability and bronchoconstriction along with stimulation of platelets and cells to form other mediators
What are important acute inflammatory cytokines?
TNF, IL-1, IL-6
What are the main functions of TNF and IL-1?
Cause endothelial activation (leukocyte binding and recruitment)
Also induce systemic effects of inflammation: Fever, acute phase protein synthesis, etc
What are the important chronic inflammatory cytokines?
IFN-γ and IL-12
What is the role of IFN-γ?
Stimulates classical macrophage activation
What is the role of IL-12?
Stimulate the growth and function of T cells
What induces the activation of IL-1?
inflammasome
What cells produce reactive oxygen species?
neutrophils and macrophages
What is the role of reactive oxygen species?
highly toxic oxidizers that not only damage microbes, but also host tissues
What is the function of nitric oxide in inflammation?
a free radical that can be used to kill microbes
A mediator of vasodilation, antagonizes platelet activation, & reduces leukocyte recruitment
How is Type II NOS stimulated?
induced in macrophages and endothelial cells
Induced by IL-1, TNF, IFN-γ and bacterial endotoxins
What pH conditions are ideal for intracellular lysosomal enzymes?
low pH
What pH conditions are ideal for extracellular lysosomal enzymes?
neutral pH
What is the role of alpha 1- antitripsin?
inhibits elastase **protease inhibitor
What is the role of alpha 2-macroglobulin
inhibits a large variety of proteinases (e.g. collagenase)
Give an example of a neuropeptide
Substance P, an 11 amino acid peptide
Secreted by nerves and inflammatory cells (macrophages, eosinophils, lymphocytes, dendritic cells)
**generates proinflammatory effects in immune and epithelial cells
What are neuropeptides active in?
vascular tone and permeability
What is the central complement factor?
C3
What are they three pathways for the formation of C3?
1) the classical pathway, triggered by fixation of the first complement component C1 to antigen-antibody complexes;
(2) the alternative pathway, triggered by bacterial polysaccharides (e.g., endotoxin)
(3) the lectin pathway, in which a plasma lectin binds to mannose residues on microbes and activates an early component of the classical pathway (but in the absence of antibodies).
What happens once C3 is cleaved?
It cleaves into C3a and B. C3b deposits on the cell or microbial surface where complement was activated and then binds to the C3 convertase complex to form C5 convertase; this complex cleaves C5 to generate C5a and C5b and initiate the final stages of assembly of C6 to C9.
What is the role of C3a and C5a?
increases vascular permeability and stimulates mast cells to release histamine
What complement molecule activates the lipogenous pathway for AA metabolism?
C5a
What complement molecules activate leukocytes increasing their endothelial adhesion?
C5a, C4a, C3a
**these are also chemotatic agents for neuts, eos, basophils and monocytes
What complement molecule acts as opsonin for enhanced phagocytosis?
C3b
What part of complement forms the MAC?
multiple C9 proteins
What protects host tissue from activated complement?
C1 inhibitor blocks activation of C1
**Decay-accelerating factor (DAF) and **factor H limit C3/C5 convertase formation
What is the role of clotting factor XII in inflammation?
important clotting factor that activates the kinin system –> ultimately leads to bradykinin which increases vascular permeability, vascular dilation and pain
What activates factor XII?
Intermediate product Kallikrein is chemotatic and activates Factor XII
what molecule down regulates macrophages?
IL-10
what molecule promotes fibrosis and is anti-inflammatory?
TGF-beta
What are the two main types of tissue repair?
Regeneration and scar formation
What cell is responsible for Growth Factor Secretion?
Macrophages
What cell is responsible for Neovascularization?
endothelial cells
What cell is responsible for Collagen deposition?
fibroblasts and myofibroblasts
What cell is responsible for Collagen remodeling / retraction?
fibroblasts
What cell is responsible for Re-epithelialization / Regeneration?
epithelial cells cells and hepatocytes
What are labile tissues?
Continuous turnover from stem cells and proliferation of mature cells (e.g. bone marrow, surface epithelia such as skin, oral cavity, GI, ducts, urothelium, etc.)
What are stabile tissues?
minimal replicative activity, although capable of proliferating in response to injury or loss of tissue mass (e.g. parenchyma of most solid organs such as liver, kidney, pancreas; also endothelial cells, fibroblasts, smooth muscle cells); with exception of liver, stable tissues have limited capacity to regenerate after injury