T cell mediated immunity and effector mechanism

Question 1

Cell mediated immunity

Answer 1

defense against intracellular microbes and B class switching

Question 2

steps of CMI

Answer 2

1- CD4 and CD8 recognize peptides from DC.
2- Ag activtaed T cell express IL2R causing clonal expansion ( autocrine binding to IL2)
3- Some CD4 Cells remain in Lymph nodes and get into follicles for class switching

Question 3

interaction between CD4 receptors and MHC2 APC

Answer 3

1- CD4 and TCR –> peptide and MHC2
2- CD3 and ITAM coprotiens
3- theta signal transduction
4- CD28 —> B7-1 and B7-2 costimulation
5- PD1 with ITIM –> PDL1 and PDL2 inhibition
6-LFA1 –> ICAM-1 adhesion

Question 4

Role of costimulation

Answer 4

CD28-B7-1 and B7-2 interaction ensures activation by microbial antigen and not harmless substance of self antigens as B7 is expressed by stimulaion by microbe

Question 5

ICOS function

Answer 5

homologus to CD28 responsible for development of Tfh cells during germinal center

Question 6

immune synapse formation

Answer 6

TCR complex, CD4 or CD8 coreceptors, CD28 moves to the center and integrins form a peripheral ring acting as a channel for delivering signals

Question 7

activation of TCR complex by ZAP70

Answer 7

1- tails of CD4 and CD8 have tyrosine kinase called Lck
2- CD3 made up of gamma, delta and epsilion and theta contain ativatory motifs with 2 ITAMs
3- Lck phosphryates trosine residues contained in ITAMS of theta and CD3 and phoshrylated ITAM become ZAP70 which is phorpylated by lick and then active Zap70 phosphrylates adaptor protiens

Question 8

Nucelear factor of activated T cell ( NFAT)

Answer 8

1- transcription factor found in cytosole and is. Ca dependent
2- phosprylation and activtion of enzyme phospholipase Cy by itk
3- activated PLCy hydrolyze PIP2 to IP3 causin rlease of Ca from smooth ER and mitochondrial will acitvate calmodulin which will activate calcinum
4- due to loss of Ca from intracellular, Ca channel allow mroe Ca in the cytosol causing acitvation of calcineurin which removes phosphate from NFAT and activtae several genes encoding for IL2 and IL2R

Question 9

Ras/Rac-map kinase pathway

Answer 9

Zap70 and adaptor protien accumlation a plasma lead to ras and rac recruitment
2- both activate MAP kinase and activate ERK and JNK causing expression of C fos JMK and C-Fos which comebine to form transcription factor AP-1 enhacning T cell transcription

Question 10

PKCθ–NF-κB pathway

Answer 10

protien kinase C activate transcription factor NF-kB making IL1, IFNy, IL6, IL12 and IL17

Question 11

IP3 kinase pathway

Answer 11

phopsrylates PIP2 to make PIP3 and PIP3 acivaate Akt protien Kinase B stimualtion antiapoptotic expression and it activates mTOR that is resposnible for protien translation and survival

Question 12

Th1 cells cytokines

Answer 12

IFNy activating macrophages againt intracellular microbes and it inhibits Th17
IL2 which activates Tc and NK
stimulation ofTH1 increased by IL2 and IFNy and inhibited by il4 and IL10

Question 13

Th2 cells

Answer 13

secrete IL4
IL5
IL13
IL10
act on eosinophils and mast cells
Increased secretion by IL4 and inhbited by IFNy

Question 14

Th17 cells

Answer 14

secrete IL17 and IL22
act on neutriphils
secretion increased by TGFbeta, IL6, IL17 and IL21 and inhibited by IFNy and IL4

Question 15

Tfh cells

Answer 15

secrete IL21
Secrete IFNy or IL4
act on B cell for antibody production

Question 16

IL2 function

Answer 16

T cell profilration and reg T cell survival from Activated T cellI

Question 17

IFNy

Answer 17

activate macrophage the classical pathway and secreted from TH1, Tc and NK

Question 18

IL4

Answer 18

IgE class switching and alternative mccrophage activation
found on TH2 and mast cells

Question 19

IL5

Answer 19

activation of eosinophils
found on Th2, mast cells and innate lymphoid cells

Question 20

IL13

Answer 20

Class switching to IgE and alternative amcrophage activation
found on Th2, mast cells and innate lymphoid cells

Question 21

IL17

Answer 21

stimualte of acute inflammation
from Th17

Question 22

IL21

Answer 22

B ell ativtaion adn Tfh differnation and from TFh

Question 23

IL22

Answer 23

maintaince of epithelial barrier
from Th17, Nk cells and innate ymphoid cells

Question 24

Th1 development

Answer 24

Mycobacterial will present peptides to DC and NK

DC–> IL12 –> activate state4
NK –> IFNy –> activate Stat1
Formation of Th1

Question 25

Th2 development

Answer 25

parasiteopsnization by Mast cells and eosino phils
secrete IL4 –> activate GATA3 and STAT6 making Th2

Question 26

Th17 cell development

Answer 26

Extracellular fungi and bacteria bind to DC
–> IL1, IL6, IL23 and TGFbeta —> activate STAT3 and + TCR —> RORyT making Th17

Question 27

how does mycobacteria evade immune system

Answer 27

inhibition of formation of phagolsysome some

Question 28

how does HSV evade

Answer 28

inhibtion of antigen presnetion by interruptinf TAP

Question 29

how does CMV evade

Answer 29

inhibit antigen presention by removing MHC1 from ER

Question 30

how does EBV evade

Answer 30

inhibition of proteasomal activity and production of iL10 inhbiting macrophage and DC activation

Question 31

how does POx virus inhbit

Answer 31

Inhibition of effector cell activation adn producetion of soluble cytokine recpetors