How cytotoxic T cells get activated by MHC-I/antigen complexes and then proceed to kill infected cells. Created by Sal Khan.
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CD8 T cells have to be activated in the secondary lymph before migrating to the site of the infected cell. Correct?
How are they activated-how would they know to move?? plz answer quickly, Ive watched so many of these videos and everyone skips this step.
*macrophages or other APC pick up antigens from the damaged/viral/cancerous host cell and present them to CD8 cytotoxic tcells?
*or, are the antigens from damaged/viral/cancerous host cell and present them to CD4 teclls- which turn into CD4 helper - which activate CD8 cytotoxic tcells?
There is a nice review written by Jeffrey C. Nolz (2015) Molecular mechanisms of CD8+ T cell trafficking and localization. 72(13):2461-2473.
This review tells you everything you need to know about T-cells movement.
This is very over simplistic. Once you are in the med school you will be learning about cross presentation. CTL are your actual effector cells. Tc cells are the precursor cells and must be activated by Th cells in order to differentiate into CTL. The CTL will then recognize and kill either virally infected or cancerous cells.
alotan2acs Those 3 cells are technically the same but they differ in function. The cytotoxic T cell is like the umbrella term(?) and it divides and a part of the population generated becomes the Memory T cells (which helps just in case the same antigen/infected cell reappears so that the dendritic cells wont have to process the pathogen and present the antigen again) and the other part becomes the effector T cells which kill the infected cells. :)
I believe that there are 2 types of t cell. Helper T cells and Cytotoxic T cells. The helper T cells recognize the MHC 2 protein, and therefore are activated and will divide into effector and memory T cells. The Cytotoxic T cells recognize the MHC 1 protein, usually on infected "suicidal " cells. And the Cytotoxic T cell will recognize this and kill the infected cell. I might be wrong, but that's how i see it
Well, I really should thank you for the spectacular explanation up there, but I'm really confused about the MHC l and MHC ll when it combined with the CD4 or CD8, I guess there are a specific roles which controls their binding together right ? thanks again man, u r awesome !
Ibrahim Aldhoon CD4+ and CD8+ just basically stabilizes the binding of MHC 1 & 2 to the T cell receptor :) oh and they also play a role in MHC restriction so that only Th1 cells bind to MHC 1 and only Th2 cells bind to MHC 2
+Ibrahim Aldhoon CD4 T cells bind MHC II on antigen presenting cells (along with co-stimulatory molecules) and become either Th1, Th2 or Th17 (might be more but i dunno), these go on to coordinate further immune responses. CD8 T cells bind MHC I on any cell (except red blood cells which have no nucleus) and are activated into Cytotoxic T cells which kill infected cells directly (via induction of apoptosis)
You do an amazing job explaining this system! When I'm looking at my lecture notes it's harder to make these connections. Now I have a question... My professor has on his notes that the dendritic cells are the only cells that carry both MHC II and MHC I. You are also saying B cells have this quality?
+Kendra Martin All nucleated cells (essentially all cells minus erytrocites) have MHC I proteins; while only APCs have MHC II proteins, however since they are also nucleated cells they carry MHC I as well.
Sam Gee is a dick, he makes it very clear what's going on and explains everything really well. The video is done very well.
The problem is you Sam Gee, not the video.
Thanks for the video Khan Academy, love you guys.
Im trying to find in your video a reference to APC licensing but can't :( Its where T helper cells bind to a dendritic cell via the mhc class 2 and cd4+, (as well as cd40-40L) and then allow the dendritic cell to express the processed peptides on the surface of their MHC 1, to allow the recruitment of cytotoxic cd8+ t cells?
Thanks a lot , actually this is the only source I completely understood the process from .Thank you again . I have a question , please . Why Tc doesn't kill B or dintritic cells while B and dintitic cells have an MHC1 proteins , like other nucleated cells ?
Hey guys. Terrific film.
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Reason why Tcyto cell binds to MHC1 is beacuse Tcyto has cd8+ signal that has its complementary receptor on Mhc1 only, plus Cd8 cells binds only to the peptide having length 9-12 A.a, So the chances of binding Tcyto to Mhc2 is not possible, but Tcyto can recognize Mhc1 which is even present on the lympho cells as they are nucleated one ,and can kill them .
Hi.Thanks for another great video,but i'd like to ask one question.Can Tcyto lymfocytes bound to the MHC2(and kill leukocyte maybe) too or they are just bounding with MHC1?And can T helper lymfocytes become activated by MHC1?
Mr. Salman I wish if you were my teacher, i'm currently in basic immunity course at collage and the doc make it boring and not understandable
I'm glad that i found your channel, you helped me a lot and made it more interesting to study :)
Thank you so much for your efforts
@MsRsclips i am sorry you have lung cancer but i am quite sure Mr. Khan was not trying to minimize cancer he was trying to show us the students how a cell infected with cancer would show itself on the cell surface. Realize also that he is not showing his face, using a pointer etc. all he has is his voice so he has to do different intonations to make his point.
Thanks alot...This is great :) Although.. Neurons (Nerve cells) doesn't have MHC-I receptors on them. (?) Isn't that correct? But except for that one type of cells, all nucleated cells DO have MHC-I receptors..
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