Immuno 9 Flashcards
What are the most efficient Ig opsonins?
IgG1 and IgG3 which bind to Fc gamma receptor 1 and 3.
They activate phagocytes.
What are the intracellular events that occur once phagocytes are activated?
Production of phagocyte oxidase which catalyzes generation of ROS in a process called “respiratory burst”.
iNOS is triggered, thus producing NO.
Secretion of hydrolytic enzymes outside the cell if pathogen is too large, (can cause tissue damage).
What is chronic granulomatous disease?
Inherited deficiency in one of many NADPH oxidase subunits, this halts production of many ROS.
Myeloperoxidase and lysosomal contents remain functional, but myeloperoxidase uses H2O2 which is no longer generated, so bacteria that generate H2O2 and don’t have catalase are at risk of lysis.
Which cell is the most versatile in PAMP and DAMP sensing?
Dendritic cells.
What happens when CD4+ cells bind to DC?
IL-17, TNF and other cytokines induce inflammation.
IFN-gamma activates macrophages.
Cytokines also stimulate antibody production.
What are super antigens?
Bacterial toxins that stimulate all the T cells of a specific family that express the TCR gene.
They bind to the TCR and MHC 2, thereby activating many more T-cells than usual, causing exhaustion of the immune system.
How do intracellular bacteria activate macrophages?
bacterial products are detected by TLRs and NLRs resulting in activation.
How do intracellular bacteria activate NK cells?
They induce expression if NK cell-activating ligands on infected cells and by stimulating dendritic and macrophage cell production of IL-12 and 15 (NK cell activating cytokines).
What is the main protective method against intracellular bacteria?
T-cell mediated immunity
How are NK cells activated?
Antibodies that bind to antigens can be recognized by FcϒRIII (CD16) receptors expressed on NK cells, resulting in NK activation.
Lack of MHC1 also activates NK cells.
What do NK cells release upon stimulation?
cytolytic granules.
IFN gamma and TNF alpha in viral infections.
IFN gamma activates macrophages.
TNF alpha promotes tumor cell killing.
What is the main method of dealing with viral infections?
Production of type 1 interferons that give rise to an antiviral state (stops RNA translation, viral gene expression, and degradation of viral RNA),
They also cause lymphocyte sequestration in lymph nodes, increasing chance for antigen encounters.
IFN 1 increase cytotoxicity of NK and Killer T-cells.
They also upregulate MHC 1 expression for CD8+ T cells.
What are some medical uses for interferons?
IFN alpha is used for hepatitis C and B in addition to some cancers.
IFN beta is used for treating multiple sclerosis.
IFN gamma is used for chronic granulomatous disease.
What cells and antibodies are used against fungal infections?
Neutrophils and macrophages for innate immunity.
Eosinophils, mast cells, and antibodies for adaptive immunity.
IgE, IgG, and IgA coat helminths and then bind to Fc receptors on eosinophils causing the release of major basic protein (cationic) which kill the helminths.
IgE on helminths can also initiate mast cell degranulation, causing bronchoconstriction and increasing local motility to expel the worms.
