new_n_lost
Forum Hero
Topics: 673
Posts: 6,144
|
Which of the following statements about the activation of CD4 + cells is incorrect?
A) Binding of peptide + MHC to the TCR results in rapid phosphorylation of tyrosine residues in proteins associated with the TCR.
B) Intracellular calcium levels rise rapidly following activation.
C) Only peptide bound in the groove of MHC class II activates the CD4 + T cells.
D) Interaction of B7 and CD28 stabilizes IL-2 mRNA so effective IL-2 translation occurs.
E) The activated cell synthesizes IL-2 and a receptor for IL-
___________________
FORUM RULES-- Those who believe in telekinesis, raise my hand. I get enough exercise just by pushing my luck --P4U World.." The pure and simple truth is rarely pure and never simple."
|
| sss sss
Forum Senior
Topics: 8
Posts: 203
|
c
|
| drduck
Forum Guru
Topics: 82
Posts: 523
|
i dont know.....i feel all are correct....why C is wrong????
plz explain...
|
| soumadoc
Forum Newbie
Topics: 9
Posts: 19
|
cc
|
| new_n_lost
Forum Hero
Topics: 673
Posts: 6,144
|
___________________
FORUM RULES-- Those who believe in telekinesis, raise my hand. I get enough exercise just by pushing my luck --P4U World.." The pure and simple truth is rarely pure and never simple."
|
| new_n_lost
Forum Hero
Topics: 673
Posts: 6,144
|
C
Agents other than peptides bound to MHC class II can activate CD4+ T cells; these include superantigens, antigens presented by CD1, and polyclonal activators. 5DTH1 rather than TH2 cells secrete cytokines that activate CD8+ T cells.
___________________
FORUM RULES-- Those who believe in telekinesis, raise my hand. I get enough exercise just by pushing my luck --P4U World.." The pure and simple truth is rarely pure and never simple."
|
| drduck
Forum Guru
Topics: 82
Posts: 523
|
oh...yes i forgot...thanks
|
| unique1
InGodITrust
Topics: 20
Posts: 1,458
|
Levinson , eighth edition, page 400 : T cells recognize only polypeptide antigens.
___________________
I can't change the direction of the wind, but I can adjust my sails to always reach my destination.
|
| GoodGirl
______________
Topics: 107
Posts: 1,500
|
???
I'm confused now too.
___________________
Prioritize & simplify.
|
| tompat
Forum Elite
Topics: 39
Posts: 345
|
yes T cells recognize only polypepetide antigens, non polypepetide antigens are called as T cell independent antigen. this is a general rule, but it fails in case of superantigens in which case antigen is not presented in mhc class II groove. superantigen binds to variable beta domain of T cell receptor and to an alpha chain of mhc class II molecule.
so the ans choice C is incorrect, point is T cell got stimulated without recognizing antigen.
|
| unique1
InGodITrust
Topics: 20
Posts: 1,458
|
Robbins ( Diseases of Immunity) :
In a minority of peripheral blood T cells and in many of the T cells associated with mucosal surfaces (e.g lung and gastrointestinal tract ), TCRs are composed of gamma delta heterodimers (instead of alpha beta heterodimers).Such TCRs recognise nonprotein molecules(e.g bacterial lipoglycans).
Hope it clears the confusion.
___________________
I can't change the direction of the wind, but I can adjust my sails to always reach my destination.
|
| GoodGirl
______________
Topics: 107
Posts: 1,500
|
Yes Unique1, I found more info on this topic in Robbins Pathology.
___________________
Prioritize & simplify.
|
| GoodGirl
______________
Topics: 107
Posts: 1,500
|
Yes Unique1, I found more info on this topic in Robbins Pathology.
___________________
Prioritize & simplify.
|
|
| |
| | | | | | | | | | | | | |
