L2.2 (L5) Recognition of AGs by AIS Flashcards
pros of innate issume system (IIS)
immediate
cons of IIS
- has limited no of receptors
- no memory generated
pros of AIS
recognition of wide range of pathogen
- have memory cells to respond to upcoming infections
- response rapid and efficient upon re exposure
cons of AIS
response to primary infection is slow aorund 5 - 10 days
relationship between AIS and IIS
what do cells fromAIS recongise
specific pathogen AGs
what are AGs
molevules that induce immune response through activation of AG specific lympohocytes
structures that can act as AG s
proteins, DNA, lipids, carbs
function of b cells
secretes specific ABs
structure of ABs
- has heavy and light regions
- hinge regions for flexibility
- variable regions
- constant regions
what is the constant region
stays the same no matter what the pathogen is
what is the variable region
different as it’s specific to pathogens
where are the hyper varaible regions found
at the sites of AG binding
process of responses of B lymphoctes to AG binding
AG recognition> activation> proliferation> differentiation > outcomes like
- AB secretion
- isotype switching
- affintity maturation
- memory B cell
what kind of AG can only T cells respond to
peptide due to having MHC
what does T cell have that is similar to B lymphocytes
T cell receptor have a structure that is similar to to Fab section of the AB or the B cell
what sections or subunits does T cell have in their structure
alpha and beta
where are the T cell receptors found
on the surface
does T cell secrete AB s
no
what happens when the AG binds to T cell receptor
there is a signalling complex (CD3) associated with the receptor
-once the binding occur, the complezx is activated and initiates signalling casade like phopphorylation
what is MHC
major histocompatibility complex containing genes coding for cell surface proteins essential for the adaptive immune system. These cell surface proteins are called MHC molecules.
types of MHC molecules
class I and II
any another glycoproteins on the surface of the T cell
CD4 AND CD8
What does CD4 interact with
class II MHC surface molecule
what does CD8 interact with
class I MHC molecule
what cells have MHC class I on their surface
alomost very cell
what cells have MHC class II
immune cells in the lymphoid tissues like T cells, B cells, Macrophages, dendirtic cells
pathway of the response of T lympohcytes to AG binding
AG recognition>lymphocyte activation > proliferation(takes time)> differentiation> effector functions like
- activation of macrophages, B cells, inflammation
- killing of infected cells
what is CDR
complementary determining regions
- polypeptide sequence of AB that is responsible for its recognition by lymphocytes.
how are ABs generated from the gene to the protein
using germline DNA to make the seqs for the chains
- the J part joins the genes for Variable and constant regions together for mRNA
- makes the polypeptide chain
how can diversity generated in the gene for ABs
- recombo for gene segments
- an enzyme (tdt) tgat is DNA polymerase nserts N-nucleotides to the V (D) J gene segment during rearrangements of genes
- somatic hyper mutation for b cells
- allelic exclusion
what is allelic exclusion
- process by which only one allele of a gene is expressed while the other allele is silenced)
- prevents the rearrangemnt of 2nd chromosome
