5: Cellular innate immunity: mast cells, eosinophils, basophils, ILCs, NK cells Flashcards
what are immune cells functions during inflammation?
attract effector cells from the blood to sites of infection
pathogen destruction
tissue damage repair
what cells play a role in innate and adaptive immunity?
mast cells, esoinophils, basophils
what is the common property of mast cells, eosinophils, and basophils?
they all contain cytoplasmic granules filled with various inflammatory and antimicrobial mediators AND are involved in immune responses that protect against helminths and reactions that cause allergic diseases
where are mast cells most abundant?
skin and mucosal epithelia (TISSUE ONLY)
what happens upon activation of mast cells?
release many potent inflammatory mediators that defend against helminthic parasites or cause symptoms of allergic diseases
what inflammatory mediators are stored in the cytoplasm of mast cells?
histamine and inflammatory lipid mediators
how does histamine cause inflammation?
promotes changes in the blood vessels
what can mast cells release besides histamine and inflammatory lipid mediators?
cytokines
mast cells express high-affinity plasma membrane receptors for which antibody?
IgE
what leads to mast cell activation?
antigen binding to the antibodies on the cell surface of the mast cell
what is the most important vasoactive molecule released by mast cells and baosphils.
histamine
what induces vascular leakage, bronchoconstriction, and intestinal hypermotility (components of the immediate immune response)?
amines and lipid mediators
chemokines released by basophils and mast cells result in the recruitment of?
blood leukocytes
where are basophils most commonly found?
in the blood circulation and may be recruited to some inflammatory sites
basophils are considered what>
blood granulocytes (similar in structure/function to mast cells)
eosinophils’ cytoplasmic granules contain enzymes that are harmful to what?
cell walls of parasites
where do eosinophils reside?
in the blood circulation and may be recruited to tissues AND normally present in peripheral tissues
in what peripheral tissues are eosinophils found?
mucosal linings of the respiratory, GI, and genitourinary tracts
what is the function of innate lymphoid cells?
act as effector cells to amplify signals delivered by innate recognition
where do innate lymphoid cells develop?
in the bone marrow from the common lymphocyte progenitor (same site that gives rise to B and T lymphocytes and NK cells)
how are ILCs grouped?
by the cytokines they produce
can innate lymphoid cells (ILCs) destroy pathogens?
no, only activate cytokines
what is the important role of ILCs?
they initiate inflammatory responses at barrier surfaces in response to infectious organisms
what is the role of group 1 ILCs?
provide resistance to viruses, intracellular bacteria and parasites by producing TNK and IFN gamma
what is the role of group 2 ILCs?
provide resistance to helminth parasites by producing IL-4,5,9,13
What is the role of group 3 ILCs?
provide resistance to extracellular bacteria by producing lymphotoxin (LT), TNF, IL-17A, IL-22
what are the properties of NK cells?
granular lymphocytes
non-phagocytic
not antigen specific
no surface immunoglobulin
where are NK cells found?
high concentration in spleen, liver, uterus, and peripheral blood
what is the lifespan of a NK cells?
7-10d
what is the primary function of NK cells?
non-specifically kill tumors or virally-infected cells, AND secrete cytokines
what cells can secrete cytokines?
any immune cell
what cells are the first line of defense to viruses and when do they peak?
NK cells; 3 d
what are the three methods of killing pathogens employed by NK cells?
natural cytotoxicity
cytotoxic cytokines
anti-body dependent cell-mediated cytotoxicity
what is natural cytotoxicity (NK cells)?
releasing of granules after binding to the ligand of a host cell causing it to die
what is cytotoxic cytokines (NK cells)?
NK cells respond to IL-12 produced by macrophages and secrete IFN gamma which activates the macrophages to kill the phagocytosed microbes
what is anti-body dependent cell-mediated cytotoxicity (NK cells)?
the Fc receptors on NK cells can bind IgG and trigger the release of cytotoxic granules on tumor cells or virus infected cells
when are NK cells involved in an infection?
early
what receptors on NK cells allow them to detect if a cell is infected or healthy?
inhibitory receptor (healthy)
activating receptor (infected)
what immunoglobulin is of central importance in allergic reactions?
IgE binds to specific Fc receptors on mast cells to activate them
