Immune Function Flashcards
What function does MHC-1 have on normal cells?
inhibits apoptosis by NK cells
How can NK cells trigger apoptosis?
1) release perforins - form a pore to allow proteases (granzymes) to enter cell –> cytosolic capsase pathway; 2) Fas-FasLigand pathway on the surface of the cell
What are the 3 types of PAMP (pathogen associated molecular patterns) receptors?
1) Secretory: act as opsonins, binding to microbial cell walls and flagging them for activation of complement and phagocytosis
2) Endocytic receptors: mediate phagocytosis by macrophages;
3) Cell-signaling: activate intracellular pathways that lead to up-regulation of cytokines to trigger an inflammatory cascade
What is the function of toll-like receptors?
specific family of signaling pattern recognition receptors that promote inflammation and the adaptive immune response via the NF-kB cascade
Toll-like receptors are very similar in structure to what interleukin?
IL-1
T/F: The cardinal features of the innate immune system are rapid, non-specific, and has no memory of past events.
TRUE
What are the cardinal features of the adaptive immune system?
specificity, diversity, memory, specialization, self-limitation (return to homeostasis), and non-reactivity to self
What are the components of the innate immune system?
physical barrier, complement, antimicrobial peptides, cytokines, macrophages, neutrophils, NK cells
What are the components of the adaptive immune system?
antigen presenting cells, lymph nodes, T-cells, B-cells
What are the key mediators that link innate and adaptive immunity?
cytokines
Pleiotropy
one cytokine can have a different effect depending on the cell type it binds to
Give an example of how IL-4 exhibits pleiotropy
IL-4 can have both stimulatory and inhibitory effects depending on the target: 1) IL-4 stimulates class switching and IgE production in B cells, growth and differentiation factor for Th2 cells, stimulates expression of adhesion molecules on vascular endothelium, mast cell growth factor; 2) Inhibitory: counter-regulatory to IFN-gamma and down regulates IL-1, IL-6, TNF-alpha secretion by macrophages
Redundancy
multiple cytokines have the same or overlaping biological functions
Give an example of redundancy with B cell proliferation
Multiple cytokines stimulate B cell proliferation (have same function): IL-4, IL-5, IL-13
IL-1 and TNF-alpha both activate macrophages and in high quantities have endocrine effects such as fever and cachexia. Is this an example of Pleiotropy, Redundancy, Synergy, Antagonism, or Cascade Induction?
Redundancy
Synergy
two or more cytokines expressed together have greater than additive effects on a cell
Antagonism
one cytokine inhibits the action of the other
Cascade Induction
cytokine effect on a target cell that induces that cell to produce the same cytokine –> rapidly spreads to adjacent cells that also produce the same or other synergistic cytokines
Interleukins
Cytokines that regulate interactions between lymphocytes and other leukocytes
Interferons
glycoproteins that are synthesized in response to viral infections, immune stimulation or chemical stimulation - inhibit viral replication by interfering with viral RNA and protein synthesis
Tumor necrosis factors
polymeric cytokines derived from macrophages and T cells - involved in immune regulation, inflammation, and programmed cell death of some tumor cells
TNF-alpha, lymphotoxins, fas ligand (CD95L), CD154 (CD40L) and CD30L are all part of what cytokine family?
tumor necrosis factors
Growth factors
also known as colony stimulating factors - stimulate cell growth and proliferation
chemokines
small proteins that act primarily as chemotactic factors or leukocyte activators
Primary cytokines are part of the innate or adaptive immune system?
innate
_____ are cytokines that by themselves initiate all events required to bring about leukocyte infiltration into the tissues.
Primary cytokines
What are examples of primary cytokines?
IL-1, TNF-alpha, TNF-beta, IL-18
_____ are cytokines whose production is induced only after cellular stimulation by a primary cytokine.
Secondary cytokines