Immunology Exam 1 Flashcards
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Contrast innate and acquired immunity (4).
- nonspecific VS specific
- common to all living things VS vertebrates
- present at birth VS developed over time
- no memory VS memory
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Examples of innate system elements (5).
- Physiological barriers
- PMLs
- Macrophages
- NK cells
- Inflammation
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endocytosis
ingestion of foreign macromolecules by pinocytosis or receptor-mediated endocytosis.
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phagocytosis
ingestion and destruction of foreign particles.
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opsonin
facilitator of phagocytosis. May be an antibody (ex IgG) or complement.
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reticuloendothelial system
includes macrophages, dendritic cells (spleen and lymph nodes), interdigitating cells of thymus, Langerhans cells in skin, and other APCs throughout the body.
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Describe the relationship between phagocytes and the acquired system.
Phagocytic cells take in antigens, process them, and present them to the lympocytes of the acquired immune system so that a specific acquired immune response (cellular and humoral) can be initiated against that antigen.
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(1) Describe the inflammatory response including (2) the hallmarks of inflammation and (3) which cells are involved.
Goal is to bring tissue back to normal. Triggered by exogenous or endogenous tissue damage.
Hallmarks: redness (rubor), pain (dolor), heat (calor), swelling (tumor) and loss of function
Cells: PMNs, macrophages and lymphocytes. PMNs show up in 30-60 mins. Mononuclears show up in 5-6 hours.
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List the 3 main cell types involved in acquired immunity and briefly describe the function of each.
-T-cells: cell-mediated response. Direct attack on infected cells, tumor cells.
- B-cells: antibody production.
- Phagocytes: antigen processing and presentation.
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Name the primary lymphatic organs and the type of cell that matures in each.
Thymus: maturation of T-cells
Bone marrow: origin of lymphocytes and maturation of B-cells.
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Name the 2 major secondary lymphoid organs and 2 major functions that occur in these organs.
- Spleen
- Lymph nodes
(1) trap and concentrate foreign antigens, and (2) main site of production of antibodies and antigen-specific T-cells
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Describe the circulation pathway of lymphocytes.
Circulate through blood, and enter lymphatic system. Re-enter circulation through thoracic duct, which empties into right atrium. Use HEV to “home in”, enter appropriate tissues through endothelial cell barrier.
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Antigen
any agent capable of binding specifically to components of immune response.
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Immunogen
any agent capable of producing an immune response.
All immunogens are antigens, but some antigens can bind without causing an immune response.
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Hapten
Non-immunogenic low MW molecules
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Adjuvant
present in vaccines and enhance immunogenicity.
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Epitope/Antigenic determinant
5-7 AAs long and serve as antibody binding sites. Do not “fit” into the conformation or chemical makeup of body’s constituents.
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Valence
number of epitopes on a molecule
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Cross reaction
2 definitions
An immunologic reaction in which cells or antibodies react with 2 molecules that have common epitopes but are otherwise dissimilar.
Cells or antibodies with specificity for 1 epitope react weakly with another epitope that structurally resembles it (but is not specific for it).
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List the four requirements for immunogenicity.
- Foreign to self
- High MW
- Chemical complexity
- Degradability (in order survive and then to be presented)
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List the 4 major classes of antigens and give an example of a diagnostically important antigen for each class.
- Carboyhydrates—ABC antigens on erythrocytes
- Lipids—cardiolipin
- Nucleic acids—autoimmune response to DNA with SLE
- Proteins—serum albumin
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Contrast epitope recognition by B cells and T cells.
B cells use sIg (surface immunoglobulin) receptors to bind free, soluble antigen
T cells use TcR, which require processing and presentation in association with MHC
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Contrast how foreign antigens entering the body through blood, skin and respiratory or gastrointestinal routes find their way to the lymphoid cells.
BLOOD: response initiated at spleen
SKIN: local inflammation; transport to lymph nodes by macrophages
GI: response initiated at MALT
examples of physiological barriers
skin and mucous membranes
fatty acids and low pH of sweat
sebaceous secretions
soluble proteins (interferons, complement)
respiratory tract (nasal hairs, cilia, cough reflex, mucus lining)
GI tract (salivary enzymes, low pH of stomach, enzymes in bile and small intestine)
4 PMNs
neutrophils, eosinophils, basophils and mast cells
macrophages activated by…
cytokines released primarily from T-cells
differentiate NKs from lymphocytes
slightly more cytoplasm, granules
NK express…
function
Express killer inhibitory receptors (KIR). KIR binds MHCI on normal cells and protects them from NK destruction. Tumor/virally infected cells have abnormal MHCI and cannot bind KIR. NK destroys them.
2 NK killing processes
(1) Creates pores in the membrane, causing lysis
(2) Triggers apoptosis.
trigger NK activity
IL-2
IL-12
interferons
endogenous inflammation causes (2)
uncontrolled immune response
abnormal clotting reactions.
inflammation releases vasoactive peptides, which cause… (4)
(1) smooth muscle contraction, (2) nerve stimulation, (3) endothelial cell contraction, and (4) expression of ECAMs (endothelial cell adhesion molecules) resulting in increased vascular permeability and recruitment of PMNs to the site.
liver proteins involved in inflammation. example.
acute-phase proteins
C-reactive protein binds to membranes of certain microbes and activates complement.
Immunization
generation of subsets of lymphocytes that can recognize an antigen upon a secondary exposure
regions and cells of thymus
Cortex contains immature cells. Medulla contains more mature cells (which have their specific receptor)
atrophy of thymus
fatty metamorphosis
required for lymphocytes to enter appropriate tissues
homing in
HEV
high endothelial venules
typical MW of immunogens
> 6000 Da
not good immunogens due to lack of variety
homopolymers
example of a hapten
cardiolipin
homologous cross reactions
occur when antigen and immunogen are the same substance
heterologous cross reactions
occur when substance that induces immune response is something other than the antigen you are trying to elicit the response against
cross reactions cause…
false positives
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Antibody
Product of the immune system that imparts protection.
Belong to a protein class called globulins, collectively known as immunoglobulins. Exhibit a high degree of specificity, therefore one part of the molecule must be adaptable to a large variety of epitopes.