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83 Cards in this Set
- Front
- Back
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When you think of adapted or acquired immunity what should you think of first?
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LYMPHOCYTES
Tcells are cell mediated (deal with MHC molecules) B cells are humoral and differentiate into plasma cells which produce antibodies |
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What differentiates an adaptive cell from an innate cell?
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adaptive cells have antigen receptors.
(B cells and Tcells) Innate cells do not have these receptors or an ability to recognize specific antigens (monocytes/ macrophages, granulocytes --neutrophil, basophil, eosinophil, dendritic cell NK cells B1 cells |
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What is the precursor to the macrophage? Where do they differentiate?
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monocyte
monocytes are circulating in the blood stream In tissues they become macrophages |
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Kupffer cells
Microglia Mesangial cells Histiocytes Osteoclasts |
Macrophages in the:
Liver Brain Kidney Connective tissues Bones |
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What is characteristic of a macrophage?
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phagocytic
produces cytokines antigen presenting microbicidal scavenger cell of the bod |
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What is characteristic of a dendritic cell?
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numerous psuedopods on membrane
high expression for MHC class II molecules antigen presenting cell |
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what do neutrophils do?
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granuolytic cells
phagocytic Fc receptors, complement receptors becomes pus in battle with pathogen |
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If neutrophils are granulocytes, what are in the granules?
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azurephilic = hydrolytic ez, myeloperioxidase and microbicidal stuff
dark granules: lysozome, lactoferrin, alkaline phosphatase |
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What is characteristic of eosinophils?
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mobile phagocytes
defense against parasites activate mast cells (allergic response initiators) |
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What is characteristic of basophils?
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Fc receptor for IgE on surface of membrane
allergic, parasitic and inflammatory responses |
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What are characteristics of mast cells?
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found everywhere, especially near epithelial surfaces
Fc receptor for IgE on surface of membrane allergic, parasitic and inflammatory responses |
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What are characteristics of NK cells?
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BIG. aka Large Granular Lymphocytes (LGL's)
Fc receptor CD56, CD16 no TCR or Ig on surface kill, kill, kill virus infected or tumor |
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What are y:B Tcells?
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somewhere in between innate and adaptive immunity. They have yB chains instead of aB and don't need MHC.
They work mostly in gut and release cytokines in event of infection |
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What are characteristics of a T cell?
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TCR and CD3 on surface
Either have CD4 or CD8 There is also yB Tcell |
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What's another name for a Tcell that expresses CD4?
What does it do? |
Helper T cell
recognizes MHC II secretes cytokines that activate effector cells (IL-2, IFNy, IL-4, IL-5) |
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What kind of cytokines do Th1 cells secrete?
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IL-2 and IFNy
helps cd8 cTL's and macrophages |
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What kind of cytokines do Th2 cells secrete?
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IL-4, IL-5
helps B cells |
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What are C TL's?
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cytotoxic T lymphocyte
CD 8 T cells MHC I recognizer initiates apoptosis |
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What are characteristics of B cells?
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Displays Ig's (antibodies) as receptors for antigen
displays MHC II acts as a professional APC after binding an antigen, B cells differentiate into plasma cells which dump a ton of Ig's into the system |
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XLA
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defective Btk gene (codes for the enzyme which matures B cells)
person is vulnerable to extracellular bacteria and viruses |
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Where does positive selection of thymocytes take place?
negative selection? |
positive selection (can recognize MHC's) in thymus cortex
negative selection (doesn't go after self) in medulla of the thymus |
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What does the spleen do?
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Specializes in filtering blood and trapping blood-born pathogens
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What is PALS and what would be the significance it its decreased or missing?
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peri-arteriolar lymphoid sheath
surrounds the splenic artery in spleen and has lots of T cells If the PALS is weak, you would assume pt. is deficient in T cells |
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What is the primary lymphoid follicle?
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area surrounding a germinal center of the spleen white pulp Has B cells
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In a lymph node, where are the B and T cells located respectively?
What about the macrophages and plasma cells? |
B cells are in primary and secondary follicles in cortex
T cells are in paracortical area macros and plasma dudes are in medulla of lymph node |
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What are BALT, GALT and MALT?
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Bronchial
Gut Mucosal --associated lymphoid tissue Create a localized reaction against a pathogen. Unlike the lymph node, these guys don't leave these tissues. |
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What are the specialized cells in GALT that take up antigen via endocytosis in the epithelium?
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m cells
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What are cytokines?
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small proteins that lots of cells release when they encounter a pathogen or invader
work in autocrine or paracrine fashion can do some endocrine action |
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What are chemokines?
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small, inducible, secreted proinflammatory cytokines
act as chemoattractant and activate specific leukocytes |
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What are complements?
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serum proteins circulating in proenzyme state
when activated take part in: --inflammation --opsoinization --damaging microbial cells |
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how does inflammation function to provide an immune response?
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localized vascular permeability is increased and it attracts macrophages.
opens up that vascular system so that fluid flows and things that need to get there to it do. |
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What are the APC's of the immune system?
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dendritic cells
macrophages B cells |
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What are the effector cells of the immune system?
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neutrophils
macrophages NK cells effector T and B cells |
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How do APC's recognize pathogens?
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A number of receptors are on their membrane.
PAMPs These receptors recognize things like proteins, glycoproteins, peptidoglycans, carbs, nucleic acids etc. i.e. Mannose and LPS go with fungi or gram + bac. and are recognized by mannose receptors and TLR4 receptors INNATE remember |
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What are adhesion molecules?
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On the endolthelium, they get upregulated when injury occurs so that the cells that are being hailed for the inflammatory response have a better chance to get slowed down and arrive at the scene
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What are the characteristics of inflammation?
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calor
dolor rubor tumor (swelling) loss of function |
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What are the differences between innate immunity and adapted immunity?
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Innate:
Fixed--no adaptation Immediate Non/limiten specificity No memory, same intensity each time self and non self discrimination is from PAMPS |
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What is the antigenic determinant or epitope?
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the molecules, macromolecules,
virus particles or any other antigen part that the Ig or TCR binds to on pathogen |
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What are typical epitopes for Abs to bind to?
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Binding of bacteria, viruses or toxins that have:
INTACT antigens --carbs --AA clusters --sometimes both |
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What epitopes do TCR bind to?
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short peptides presented to them by MHC's
(broken down bits of pathogen) |
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What's the difference between a TH1 cell and a TH2 cell?
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These both arise from CD4 receptors on Th cells binding to MHC II APC.
Th1 cells recruit macrophages to help Th2 cells recruit B cells to help |
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Neutralization
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Ab can bind intact pathogen and toxin and inhibit their function or limit their interaction with our human cells
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opsonization
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IgG coats the surface of extracellular pathogens and toxins so they can be easily eaten by phagocytes
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complement activation
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Ag:Ab complex rally complement proteins which opsonize the bug. Has specificity for phagocytes
IgG=reg opsonization or complement opsonization IgM= ONLY complement opsonization |
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what does positive selection in the thymus cortex mean for thymocytes?
What about negative selection in the medulla? |
If those thymocytes are able to bind to MHC's then they are selected (so we know they'll work)
negative selection weeds out those guys that will bind to self antigens |
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What are the subsets of Tcells?
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Th1--recruit macrophages
Th2-recruit B cells CTL--kills |
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What are the characteristics of adaptive immunity?
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adaptive
slow specific memory discrimination between self and non self diverse response |
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explain how a coxsackie virus infection may cause IDDM.
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Previous infection of coxsackie elicits adaptive immunity to create an antibody that also reacts with self MHC B cells of pancreas. Those T cells attack the pancreas B cells and destroy their ability to make insulin
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What is VCAM-1?
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cell adhesion molecule
on the stromal cell interacts with VLA-4 on pro-B cell |
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What is C-kit?
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a receptor on pro b cells
interacts with SCF (stem cell factor) on stromal cell after VCAM-1 has bound to VLA-4 |
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How does IL-7 play a role in B cell maturation?
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released by stromal cells,
leads to down regulation of adhesion molecules on pre-B cells so they can detach from stromal cell needed for growth and maturation |
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What designates the change from late pro-Bcell to pre B cell?
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expression of IL-7 receptors
detachment from stromal cell rearrangement of heavy chain (Dh to Jh and then Vh to DhJh) expression of Mue chain |
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What is the Mue chain?
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Expressed once heavy chain rearrangement has occured and you now have a Large Pre B cell
associated with a surrogate light chain and Iga and IgB |
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What is happening during the pre-B cell phase?
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light chain rearrangement
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X linked agammaglobulinemia
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No circulating antibodies
development is halted at Pre B Cell stage staph, strep and haemophilus infections |
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What are the 2 light chain rearrangement options?
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Kappa and Lambda
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What is the committed antigenic specificity of an immature B cell determined by?
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Heavy chain VDJ sequence and light chain VJ sequence
IgM is expressed on surface |
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burkitt's lymphoma
FAB L3 |
due to mistake in Ig gene rearrangement
Genes get mixed with a myc proto oncogene and proliferates into B cell tumors |
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What does an immature B cell have to have to be considered naive mature B cells?
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expression of IgD and IgM
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Define negative selection which accounts for only 10% of the B-cells that are produced in the bone marrow that actually become a B cell
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When immature B cells react to self antigents apoptosis occurs
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Multiple myeloma
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malignancy of plasma cells
plasma cell tumors in bone marrow cause local erosions of the bone IgG or IgA excess production (which are secreted in urine "bence jones" proteins) |
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Humoral immunity
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SECRETED ABs
neutralize microbes / toxins opsonization / phagos complement activation |
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What are the humoral immunity Abs?
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Ig...
A, G, M, D, E |
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What is a secreted Ab made of ?
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2 light chains,
2 heavy chains noncovalent bonds and disulfide bonds |
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papain and pepsin
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proteolytic cleavers that allow for Ab rearrangement
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How do B cells get activated?
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BCR's bind to the antigen and with the help of IgM, Iga and IgB send a signal to make antibodies
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What are some TI (thymus independent Ags?
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bacteria polysaccharides
lipopolysaccharides, peptidoglycans Ag's that are different enough they don't need CD4 T helper cells to activate naive B cells |
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What happens in a patient with no thymus?
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They can make Ab's to bacterial polysaccharides, lipopolysaccharides, and peptidoglycans without their thymus
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Where are thymus dependent antigens brought in contact with B cells?
How is this done? |
lymph tissues
travel thru HEV (high endothelial venules) and are processed and presented by APC's (dendritic cells or macros) |
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What type of T cells work with B cells in the lymph tissue?
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CD4 T Helper cells
recognize MHCII on B cells |
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What are effector functions of secreted Abs?
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neutralization
opsonization complement activation |
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How does neutralization occur when an Ab binds to an ag?
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prevents bacterial adherence so it can't attach to cells.
also blocks binding toxins and viruses |
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how does opsonization by secreted ab's work?
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marks ag for phagocytosis
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What happens to an ag once the complement cascade has been activated?
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enhanced opsonization
lyses some bacteria |
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What is ADCC?
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Antibody dependent cell mediated cytotoxicity
Antibody traps Ag on target cell surfaces NK cells have Fc receptors that come along and bind to Ab and this triggers NK to kill target cell |
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What significance does C3 play in humoral immunity?
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Activation of all 3 pathways of the complement cascade lead to the cleavage of C3 into C3a and C3b.
C3b binds to Ag and increases opsonization because phagocytes recognize C3b C3a leads to inflammation |
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What are the complement dudes that make the MAC?
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C5b, C6, C7, C8 and this complex leads to the polymerization of C9 to make the pore
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What is isotype switching?
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a biological mechanism that changes a B cell's production of antibody from one class to another, for example, from an isotype called IgM to an isotype called IgG. During this process, the constant region portion of the antibody heavy chain is changed, but the variable region of the heavy chain stays the same (the terms "constant" and "variable" refer to changes or lack thereof between antibodies that target different epitopes). Since the variable region does not change, class switching does not affect antigen specificity. Instead, the antibody retains affinity for the same antigens, but can interact with different effector molecules
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What are the characteristics of IgM Abs?
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1st responder
in blood and ECF bind and activate complement pentamer (allows to bind to particulate ag) no Fc region to recruit phagocytes |
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What are the characteristics for IgG abs?
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2nd responder
blood bourne bind and activate complement can cross placental barrier (passive immunity for baby) with IgM, prevent septicemia |
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What are characteristics of IgA ab?
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monomeric
found in fluids and tissues Dimeric found in epithelial tissue MALT--mucosal breastfeeding confers passive immunity to baby |
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What are the characteristics of IgE ab?
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binds Fc regions of mast cells, basophils and eosinophils
mucosa of GI and respiratory tracts and skin dermis Histamine inflammatory mediators cause all the swelling, redness, mem perm, contraction of smooth muscles to eject parasites |
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What is the FceRI receptors on Mast cells / basophils and eosinophils?
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binding of ag results in immediate effector function
each mast cell, basophil , eosin can react to multiple ag's. |
