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Innate and Acquired Immunity (Acquired/ Adaptive Immunity (Both Innate and…
Innate and Acquired Immunity
Innate Immunity
Physical and chemical barriers
Skin
Glands
Mucous Membranes
Macrophages
proteolytic enzymes
fatty acid secretions (lysozymic enzymes)
Pattern of recognition
hallmark of innate immunity
PRRs
detection of PAMPs occurs via Pattern Recognition Receptors (PRR's) respond to PAMPs (Pathogen Associated molecular patterns)
B and T lymphocytes express some of PRR's somatically but these are thorugh a series of genes expressed through development
many PRRs are highly expressed on DC - highly efficient APC's- where they can be located on the cell surface, in endocytic compartments, or in the cytoplasm
These processes make it possible for the adaptive immune system to have a response which is longer lasting
Toll Like Receptors
expressed as membrane bound receptor or cytoplasmic receptor
Recognizes large number of PAMPs by Viral, bacterial, fungal and parasitic pathogens
TLR1,2,4,5 and 6 are plasma membrane expressed
TLR3,7,8,9 traffic from ER to endolysosomal compartments where they recognize RNA and DNA
Complement System
proteins made in the liver that assist or complement the action of antibodies destroying bacteria
Complement cascade
membrane attack complex ( MAC) which are inserted in cell walls that surround invading bacteria resulting in holes in membrane causing fluid to flow out of bacteria and eventual cell lysis
3 pathways
classical activation pathway ( adaptive immune response) which is when the first protein in the complement cascade is activated by the antibody, it generates a chain of events which cause MAC production and attachment to bacteria or microbe and eventual cell lysis
alternative activation pathway
direct binding of complement proteins with out participation of antibodies, triggering a conformational change in the protein leading a downstream cascade leadig to generation of MAC followed by lysis of microbe
lectin activation pathways
involves other complement such as C2 and C4 which are lectins that bind directly, resulting in MAC production and lysis of microbe.
Inflammation
normal immunological process designed to restore immune homeostasis by bringing injured tissue back to its normal state/
classic signs:: pain redness heat
Acquired/ Adaptive Immunity
based on the use of antibodies to incite an immunological response based on prior contact with pathogen or microbe.
this immune response is much longer to respond than innate immunity
Acquired immunity is based on the innate immune response to a pathogen and the recognition of said pathogen to cause a T-cell led response which more efficiently destroys the pathogen
antigen specific lymphocytes and memory cells prevent reinfection by same organism
B-cells expressing B-cell receptors synthesize and secrete antibodies into the blood stream which is termed Humoral immunity.
Tcell express varied T cell subsets and cytokines which are cellmediated response or cellular immunity
Antigenpresenting cells such as macrophages and dendritic cells display processed major histocompaticility complex bound to peptides derived from the antigens
requires 2 things to activate T-cell
T-ce;; expression of peptide(epitope)-specific TCRs
Ligation of T-cell expressed co-stimulatory molecules with complimentary membrane molecules expressed by APCs
Retuculonlithelial system
traps antigens
provides loci for T-cells, B cells, macrophages and antigens can interact within a small area to initiate an immune response
Both Innate and adaptive immune systems work in tandem in order to function properly
they communicate and send each other signals
activate each other
activate through various cytokines and cell adhesion molecules allowing the systems to interact
ANY innate Immune system or mechanism that can be triggered by an antigen receptor or presence of antibodys are considered adaptive immunity due to the nature of antibody production
In order for adaptive immunity to occur the body needs to see the pathogen initially to have a responses so it is ready when it occurs again.
Cells
Differentiation pathway:
Pluripotent stem cell ( bone marrow)
Common lymphoid progenitor ( Bone Marrow)
B Cell Precursor ( bone Marrow)
B cells ( bone marrow)
B cells area's of lymph nodes, spleen, Peyer's Patches, and tonsils
T-Cell Precursor (bone marrow)
In thymus: NK Cell
T Cell ( in Thymus)
T- dependant area's of lymphnodes and spleen
Myeloid Progenitor ( bone Marrow)
Megakaryocyte
Platelets (Bone Marrow)
Erythroblast
Erythrocyte( bone marrow)
Monocyte
in bone marrow => dendritic cell
In Blood => marcrophage
Tissues have macrophages, dendritic cells, and mast cells
Eosinophil ( bone marrow)
Basophil ( Bone marrow)
Neutrophil ( bone marrow)
Cell Function
Polymorphonuclear Leukocytes
Reffered to as granulocytes
Include Basophils, neutrophils, and eosinophils
short lived phagocytic cells which contain enzyme rick lysozomes facilitating destruction of infectious organisms.
Produce peroxide, superoxide radicals, and nitric oxide
Bactericidal proteins ex) Lactoferrin
Macrophages
derived from blood monocytes
abundant in cytoplasm, little ER, and many granules
Undergo further differentiation depending on tissue
Kupffer cells
in liver, large cells with many cytoplasmic projections
alveolar macrophages
in lungs to destroy any microbes that enter respiratory tract
Splenic macrophages
in red pulp
Perioneal macrophages
free floating in peritoneal fluid
Microglial cells in the CNS
All of the above are a part of the reticuloendothelial system (RES)
Major function is to phagocytize microbes and foreign substances in the blood stream and tissue
Also phagocytize aged and imperfect cells like eythrocytes
Dendritic Cells
Important to innate immunity due to their highly efficient APC properties.
enables them to trigger adaptive immune response carried out by T cells
in blood, nonmigratory follicular dendritic cells, interdigitating cells of the thymus, and langerhans cells in the skin
plasmacystoid DC
differentiated by their ability to produce large amounts of alpha/ beta interferons,
NK cells
altered features of abnormal cells are recognized by NK Cells which are cytotoxic
role in early stages of virus infection and tumorogenesis before large amounts of cytotoxic T cells and lymphocytes are generated
can lyse cells without prior stimulation
when in conact with large cell, releases molecules that can form pores, leading to lysis, or release apoptosis stimulating factors.
Lack antigen specific receptors
use cell to cell contact to determine which large cell to target
Respond to Killer cell inhibitory receptors
these KIR bind to MHC class 1 molecules expressed in normal cells
lack of receptors indicate abnormal cells and triggers NK cell action
NK T Cells
restricted variability
diffrentiate from thymic precursor during TCR engagement
. Following activation, they secrete several regulatory cytokines, including interleukin-4 (IL-4) and interferon-γ and kill target cells via Fas–Fas ligand interactions that cause apoptosis
regulate a range of immunopathological conditions
Innate Lymphoid cells
heterogenous family of innate immune cells to aide in protective immunity at acute phase of infections, tissue remodeling, anatominal containment of commensals microbes, wound healing and maintaining epithelial integrity
Producer of cytokines
soluble mediators of immune response
influence the f(x) properties of other cell types within the immune system
ex) enhance phagocytic activity