T Cell Development

This video describes the process of T cell development.

This video is from:
Janeway's Immunobiology, 7th Edition
Murphy, Travers, & Walport
ISBN: 978-0-8153-4123-9

Category:

Science & Technology

Tags:

• immunology
• cell
• biology
• development
• cells
• medical
• garland
• science
• garlandscience

[WatchOut20Me]

@Atena212 Negative selection occurs in 3 scenarios:

1)Some TcR are abnormal (due to faulty rearrangement).

2)Resulting TcR is unable to interact with any HLA molecule.

3)small percentage die due to a strong interaction with the HLA peptide complex. The peptide in the complex is self antigen so strong interaction with the HLA peptide complex will signal cell death ---> tolerance to self antigens.

Hope this helps

[Wimzig]

@WatchOut20Me I don't think a lack of interaction with HLA is strictly speaking "negative selection", rather it's just "death by neglect". Negative selection (or central tolerance, as stated in the video), is an active process to remove T cells with TCRs that have too high affinity (though I'm not sure about avidity, as the video says it is) for HLA(MHC)/self peptide complexes.

[shellybirdy]

good work here

[andrewzds]

thank you so much 4 the video!!!

[xtremetom180]

some really good stuff here

[Mephalay]

Allahın işine bak.

[RonB0105]

This is an excellent video!!!!

[tsf2ba]

great video...:)

[Wimzig]

@Wimzig Before alpha-chain rearrangement, both CD4 and CD8 are expressed on the T cell surface with a surrogate alpha-chain allowing the TCR to function. Positive selection already acts here and continues as alpha-chain rearrangement occurs. The alpha-chain gene conformation does not consist of any D segments and the rearrangement results in junctional diversity only between V and J segments. The rearranged alpha-chain replaces the surrogate if it passes positive selection. Hope that helps!

[Wimzig]

@Wimzig The random V segments you're left with encode two of the complementarity determining regions (CDR - these are the areas on the part of the TCR that define which peptide/MHC complexes it can recognise) on the variable region of the beta chain of the TCR. The third CDR is defined by the junctional diversity at VDJ junctions. CDR3 is the most variable CDR in TCRs and makes the major contact with the peptide in the MHC groove. Alpha-chain rearrangement follows beta-chain rearrangement.

[Wimzig]

@Wimzig First, there is a random loss of D and J segments so that the junction between the two segments is also random (e.g. if you have D segments 1 to 27 next to J segments 1-6, D segments 19-27 and J segments 1-4 might be randomly lost, leaving D18 next to J5). Next, there is random loss of some of the V segments, again giving a random arrangement of segments at junctions ("junctional diversity").

[Wimzig]

@jesuistahmid The T cell receptor (TCR) consists of a beta-chain and an alpha-chain, both with variable regions that specify which peptide/MHC complex the receptor will bind. In the thymus, beta-chain rearrangement occurs before alpha-chain rearrangement. Beta-chain gene configuration consists of "variable (V)", "diversity (D)" and "junctional (J)" gene segments. Rearrangement of all of these contributes to the specificity of the variable region of the TCR.