adaptive immunity response

Question 1

how are T cells activated

Answer 1

T cells can’t react to pathogen. must be first activated by an APC which shows T cells what pathogen is/loooks like and hw it should be dealt with

Question 2

how is an APC activated

Answer 2

its activated by signal showing there is an invader. then goes and activates T cells

Question 3

what are the locations of APC’s

Answer 3

mucosa associate lymphoid tissue;
Skin (SALT)
mucous membranes (GALT, BALT, NALT, GUALT)
tonsils and payers patches
also present in lymphoid organs and myeloid, plasmacytoid and dendritic are all present in the blood circulation

Question 4

what is the capture method of APC’s

Answer 4

phagocytosis and macropinocytosis (if particle is soluble)

Question 5

what are the different types of PRR on an APC

Answer 5

extracellular for bacteria and intracellular for virus

Question 6

name some examples of PRR’s on APC

Answer 6

gram pos staphylococcus aureus and streptococcus pneumoniae use PRR’s TLR1 and TLR2. neisseria meningitides and e.coli both use receptors TLR4 and TLR5. these are bacteria so PRR’s are on outside of cell
adenovirus uses TLR9 and norovirus uses TLR8. these are virus’ so are found on the inside of the APC

Question 7

what are the types of APC and where are they found

Answer 7

dendritic - lymph nodes, mucous membranes and blood
langerhan- found in skin
macrophages- various tissues
B cells- lymphoid tissues

Question 8

how is the antigen presented so immune system is warned of infection

Answer 8

using a MHC (Masterhistocompatilbility complex) or HLA (mean the same thing)

Question 9

what are the 2 classes of MHC

Answer 9

class 1- HLA A and C 
expressed on ALL nucleated cells 
class 2- HLA DR, DQ and DP 
expressed on dendrticicells,, macrophages and B cells (types of APC)

Question 10

name some features on MHC’s

Answer 10

both maternal and paternal class 1 and 2 expressed on each person 
there are many types of alleles and proteins of MHC's 
this means there is a high number of different MHC's and therefore antigens presented amongst the population meaning a better chance of survival during epidemics.

Question 11

what is the nomenclature of MHC’s

Answer 11

HLA - A1
A= locus
1= allele family

Question 12

what are the functions of APC

Answer 12

they process micbrobes via exogenous pathway or endogenous pathway and then present microbial proteins. extracellular ones by MHC class 2 (bacteria) and intracellular by MHC class 1 (virus)

Question 13

how are intracellular microbes processed via endogenous pathway (virus)

Answer 13

1. micobe in cytosol
2. marked by proteosome
3. proteasome generated peptide transporters to ER by TAP proteins
4. MHC class 1 formed
   occurs in all cell types
   MHC is present to CD8+ cells

Question 14

how are extracellular pathogen processed via exogenous pathway (bacteria)

Answer 14

1. microbes are captured by phagocytosis
2. degraded and fused with vesicles containing MHC class 2 molecules
3. if correct match form MHC class 2
4. only occurs in APC
   present ti CD4+ T cells

Question 15

how does peptide presentation by MHC’s work

Answer 15

MHC has peptide binding cleft. its broadly specific (many peptides presented by same MHC) and then these MHC’s are recognised by specific T cells

Question 16

summary of extracellular pathway for bacteria

Answer 16

PAMPs of bacteria are recognised and pathogen bound by PRR’s. exogenous pathway leads to MHC class 2 which are then recognised my CD4+ T cells. this results in humeral immune response where antibodies produced, complement system activated and phagocytosis activated

Question 17

summary of intracellular pathway for virus

Answer 17

PAMP’s recognised and bound by PRR’s. endogenous pathway leads to activation of MHC class 1 which is recognised by CD8 + T cells which results in cell independent immunity where cytotoxic t lymphocytes are activated (kill virally infected cells), antibodies are produced and macrophages are activated

Question 18

what is the clinical relevance of different MHC

Answer 18

host cells deal with variety of microbes and because have different MHC’s (no 2 individuals have the same) meaning people have different susceptibility/imune resorbs to different infections meaning it prevents whole population form being wiped out by 1 epidemic

Question 19

what are some clinical problems with different MHC’s

Answer 19

can cause organ transplant rejection because HLA mismatch and certain HLA’s are also associated with autoimmune diseases e.g diabetes.