immune system-biochem Flashcards
(45 cards)
innate immune system
derive from myeloid precursors whereas cells associated with the adaptive immune system are derived from common lymphoid precursor
one exception ….
natural killer cells are lymphocytes but NOT adaptive
examples of granulocytes
mast cells, eosinophils, basophils, neutrophils
mast cell
release mediators that trigger permeability,vasodilation,chemotaxis e.g. histamine allergic response
eosinophils
attacks parasites allergic reaction
basophils
involved in parasite defence
neutrophils
army foot soldier,phagocutes,signal to other parts of the immunes system
examples of antigen presenting cells
macrophages,dendritic cells,B-cells
macrophages
phagocytose-remove dead cells and debris -communicate with other immune cells,initaite adaptive immune system
dendritic cells
phagocytose
communicate with other immune cells
bridge between innate and adaptive immunity
initiate immune response
b-cells
present antigen to Tcells->cytokines
clonal expansion
antibodies
which immune cells are both phagocytic and antigen presenting cells
DENDRITIC cells
cytokines-activating T cell mediated response
il-12, IL-2,interfeorn-IFN-y,tumour necrosis factor-TNF-a
TH1=CD8=cytotoxic,T cells ,NK cells, macrophages,Bcells
cytokines activating antibody production-humeral response
IL-4,IL-5,IL-13
TH2=B cells,granulocytes
(eosinophils, parasite, extracellular)
complement cascade
part of the innate immune system C5a-chemotaxis C3b-opsonisation C5a and C3a-mast cell activation C5b...C9->forms a hole called membrane attack complex:cell LYSIS
lectin pathway
mannose binding lectin is produced in the liver in response to inflammation or ficolin in plasma.The MBL binds to carbohydrate on the surface of the pathogen, triggering the cascade
classical pathway
an antibody binds to a pathogen, and the antibody-antigen complex triggers the cascade
alternative pathway
a complement protein binds to a carbohydrate on the surface of the pathogen, and this triggers the cascade
leukocytes are recruited to the site of tissue injury by what
chemotaxis:process of bringing immune cells where the pathogen is
thanks to chemokine and complement proteins C5a
MHC 1
all nucleated body cells
important for :
1-Natural killer cells-perforin-poke holes in infected cell membrane
2-cytotoxic T cells(CD8)-perforin and granzymes(to kill need to recognise MHC1 with viral peptide on the surface of the virally infected cell)
bacterial infection
- break in epithelial cell
- bacteria enters and proliferates
- PPRs on macrophage recognises PAMPs on bacteria
- macrophages phagocytose the bacteria and release pro inflammatory cytokines and chemokine
- mast cell degranulation:histamine,leaky blood vessels,increased blood flow
- leukocyte recruitment:neutrophils get drawn to the area by complement(C5a), bacteria products and chemokine
- opsonised bacteria:CRP and complement proteins (C3b) act as opsonins
- neutrophils phagocytose bacteria
- dendritic cells engulf and internalise bacteria,beoming antigen presenting cells, then migrate to lymph nodes
- naive T cells are recruited to the lymph node by dendritic cells,which present the bacterial antigen on their MHC 11 complex
- B cells present the antigen on their MHC II
- antibodies opsonise and agglutinise pathogens so they can be engulfed by phagocytes
which class of MHC would be important for generating antibodies
MHC 2
dendritic cell->naive T cell->TH2 cell->activated B cell->plasma c->antibodies
viral infection
1-vrius enters the host cell and replicates
2-infected host cell release IFN-a and display parts of viral peptide on their surface MHC 1
3-virus kills infected cells. released viral particles activates dendritic cells->engulf the particles->becoming antigen presenting cells, then migrate to lymph nodes
4-naive T cells are recruited to the lymph node by dendritic cells, which preens the viral antigen on their MHC II complex
5-B cells present the antigen on their MHC II,then TH2 recognises it causing B cells to become plasma cells and produce antibodies
6-activated TH1 cells activates Cytotoxic T cells (CD8) by releasing cytokines..then they leave the lymph node and go to site of infection
7-cytotoxic T cells recognise virally infected host cells by their MHC 1 molecule which present the viral peptide on their surface..then cytotoxic cells kill them
8-natural killer cells get activated by IFN-a released by the infected cells and IL-2 and IFN-y released by TH1 cells.
9-virally infected cells secrete toxins and express viral proteins.
which subset of T lymphocytes would promote a cytotoxic T cell response
TH1
cytotoxic T cell->cell mediated
a viral infection is usually fought by a cell mediated adaptive immune response using which cell type
CD8=cytotoxic T lymphocytes
recognise virally infected host cells by their MHC1 molecule which present the viral peptide on their surface
