Download Immune system

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J. Ochotná
* autoantigen
*
*
- antigen derived from his own body
exoantigen - alien substance from the external environment
allergen - exoantigen that in susceptible individuals may
cause pathological (allergic) immune response
Secondary lymphoid tissues and organs
Fagosome fusion with lysosomes
* bactericidal substances (defensins)
* hydrolytic enzymes (cathepsin, lysozyme)
* liquid with a pH of 4-5
activation of membrane NADPH oxidase
* activation of Fc receptors and complement receptors
leads to respiratory (oxidative) flash
* oxygen intermediates (superoxid radical O2-, singlet
oxygen, hydrogen peroxide, hydroxyl radical) → damage
of the pathogen
production of nitric oxide (NO)
* macrophages produce NO after activation with
cytokines (IFNg, TNF) that are produced by TH1
lymphocytes
* NO liquidate intracellular parasites of macrophages
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lymphoid cells which belon to innate immune mechanisms
kill cells which have abnormally low MHCgpI expression
(some tumor and virus infected cells)
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have similar cytotoxic mechanisms as Tc
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NK cells activators - IFNa, IFNb
NK cells receptors
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Activating receptors - Some surface lectins, Fc receptor CD16
ADCC (antibody-dependent cellular cytotoxicity) NK cells
recognize cell opsonized with IgG antibodies by the Fc receptor
CD16, this leads to the activation of cytotoxic mechanisms (NK
degranulation)
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Inhibitory receptors - recognize MHC gpI
 Imunoglobulin family - KIR (killer cell immunoglobulin
like receptors)
 C-type lektin family - eg CD94/NKG2
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The resulting reaction of NK cell after meeting with
another cell depends on which signal prevail, whether
activating or inhibitory signals
Cytotoxic granules contain perforin and granzyme
(perforin creates pores in the cytoplasmic membrane of
target cells, in some cases may cause osmotic lysis of
the target cell, formed pores in the cell receiving
granzymes, that cause the target cell to die by
apoptosis.
Fas ligand (FasL) - which binds to the apoptotic
receptor Fas (CD95) presented on the surface of many
different cells
TNFa
NK cell activates in target cell apoptosis
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Belongs to the humoral component of non-specific
mechanisms
IFNa - produced by virus infected lymphocytes,
monocytes and macrophages
IFNb - produced by virus-infected fibroblasts and
epithelial cells
IFNa and IFNb - bind to receptors on the surface of
infected and healthy cells and induce in them an antiviral
state (synthesis of enzymes that block viral replication in
the cell)
IFNg - produced by TH1 cells, has regulatory function,
activates macrophages and stimulates the expression of
MHCgp
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Mucosal mast cells - in the mucous membranes of
respiratory and gastrointestinal tract, participate in
parasitosis and allergy
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Connective tissue mast cells - the connective tissue, in
parasitosis and allergy are not participating
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Defense against parasitic infections
In pathological circumstances, responsible for the early
type of hypersensitivity (immunopathological reaction
typeI)
Apply during inflammation, in angiogenesis, in tissue
remodeling
Regulation of immune response
Mast cells degranulation can be stimulated by:
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cross-linking of IgE Fc receptors
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anafylatoxins (C3a, C4a, C5a)
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TLR
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Establishing of multivalent antigen (multicellular parasite)
to IgE linked to highaffinnity Fc receptor for IgE (FcRI)
Aggregation of several molecules FcRI
Initiate mast cell degranulation (cytoplasmic granules mergers
with the surface membrane and release their contents)
Activation of arachidonic acid metabolism (leukotriene C4,
prostaglandin D2)
Production of cytokines (TNF, TGF , IL-4, 5,6 ...)
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Cytoplasmatic granules: hydrolytic enzymes, heparin,
chondroitin sulphate, histamine, serotonin
Histamine causes vasodilation, increased vascular
permeability, erythema, edema, itching, contraction of
bronchial smooth muscle, increases intestinal peristalsis,
increased mucus secretion of mucosal glands in the
respiratory tract and GIT (helps eliminate the parasite)
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Arachidonic acid metabolites (leukotriene C4, prostaglandin
D2)
Cytokines (TNF, TGF b, IL-4, 5,6 ...)
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Differentiate from myeloid precursor
They are considered to be the circulating form of mast
cells
Receptor equipment, containing granules, the
mechanisms of stimulation and functions are very
similar to mast cells
They are responsible for the emergence of anaphylactic
shock