A231Immunology P05 by LIM JEAN WEN https://padlet.com/190242601/5zlascbmznppzg1v Made with good vibes en-us 2020-05-27 01:33:21 UTC 2026-01-28 05:59:59 UTC hello@padlet.com T Cell Receptor 19023976 https://padlet.com/190242601/5zlascbmznppzg1v/wish/595983423 - They are receptors on the cell membrane of T cells
- Have an alpha & beta chain
- ANCHORED on surface of cell membrane
- Very specific ( in terms of structure ; must bind to peptide antigen & MHC )

T Helper Cell TCR
- Antigen binding site on the variable region of the TCR
- Co-receptor, CD4 present. This is just a marker protein

T Cytotoxic Cell TCR
- Antigen binding site on the variable region of the TCR 
- Co-receptor, CD8 present. This is just a marker protein ]]> 2020-05-27 01:47:08 UTC https://padlet.com/190242601/5zlascbmznppzg1v/wish/595983423 Major Histocompatibility Complex 19023976 https://padlet.com/190242601/5zlascbmznppzg1v/wish/595983562 Gene cluster, whose proteins present antigens to T cells

MHC Class 1
* Found on Most cells in the body
* Binds to CD8 molecules on T cells
* 1 Anchor to Cell Membrane, this is known as trans-membrane domain

MHC Class 2
* Found on Macrophages, Dendritic cells & B cells
* Binds to CD4 molecules on T cells
* 2 Anchor to Cell Membrane , this is known as trans-membrane domain


Polygenic ;  Multiple copies of the same gene one one chromosome
- Individual possess a set of MHC molecules, with different ranges of peptide-binding specificity

Polymorphism ; Many allele of the same gene in a population
MHC IS BOTH POLYMORPHIC & POLYGENIC ]]> 2020-05-27 01:47:18 UTC https://padlet.com/190242601/5zlascbmznppzg1v/wish/595983562 190242601 https://padlet.com/190242601/5zlascbmznppzg1v/wish/595983568 ♡ MHC has 2 types - 1 and 2
♡ MHC 1 works with the cytotoxic T cells, MHC 2 works with the helper T cells]]> 2020-05-27 01:47:18 UTC https://padlet.com/190242601/5zlascbmznppzg1v/wish/595983568 BCR vs TCR 19013395_2 https://padlet.com/190242601/5zlascbmznppzg1v/wish/595992269 -  BCR has heavy and light chains. It consists of a Fab and Fc region.
- BCR can bind to both soluble or cell associated antigens.
- TCR has alpha and beta chains, without an Fc region
- TCR will only bind to peptide antigens with either a Class I or Class II MHC (major histocompatibility complex), or continuous epitopes on peptide antigens.
]]> 2020-05-27 01:56:56 UTC https://padlet.com/190242601/5zlascbmznppzg1v/wish/595992269 Process *VOMITS* 19023976 https://padlet.com/190242601/5zlascbmznppzg1v/wish/595999045 T cell receptor (TCR) is found on T cells.  T cells BIND ONLY to processed peptide fragment presented on MHC on APC. 

MHC Class 2 is found on Antigen-presenting cells, which are Macrophages, Dendritic cells & B cells. They are responsible for presenting exogenous proteins.  Peptide antigen is presented by MHC class 2 molecule on surface of target cell to the T cell receptor of CD84 T cells. 

MHC Class 1 is then found on all nucleated T cells. They are responsible for presenting endogenous proteins.  Peptide antigen is presneted by MHC class 1 molecule on surface of target cell to the CD8 T cells. 

NO RECOGNITION : 
- Unbound antigen 
- Wrong peptide presented 
- Wrong MHC Class ]]> 2020-05-27 02:04:40 UTC https://padlet.com/190242601/5zlascbmznppzg1v/wish/595999045 19013395_2 https://padlet.com/190242601/5zlascbmznppzg1v/wish/596009897 Human MHC is called human leukocyte antigen (HLA) that is unique to each person
Class I MHC: HLA-A, HLA-B, HLA-C
Class II MHC: HLA-DP, HLA-DQ, HLA-DR]]> 2020-05-27 02:17:09 UTC https://padlet.com/190242601/5zlascbmznppzg1v/wish/596009897 VIDEO THINGIES ; https://www.youtube.com/watch?v=WdCiaIS2LV4 19023976 https://padlet.com/190242601/5zlascbmznppzg1v/wish/596022897 1. Recognition
- Viral antigen on MHC Class 1 binds to TCR of Cytotoxci T cells
2. Activation
-  Cytokines released 
3. Effector Function 
-  Perforin releases granzymes
- Perforin pore is formed on the target cell 
- Granzymes enter the perforin pore 
- Apoptosis of infected cell ]]> 2020-05-27 02:33:11 UTC https://padlet.com/190242601/5zlascbmznppzg1v/wish/596022897 Activation of T cells 19013395_2 https://padlet.com/190242601/5zlascbmznppzg1v/wish/596069030 Through PRR, PAMP activates dendritic cells that can then activate naive CD4 and CD8 T cells
3 signals provided by dendritic cells:
  1. Peptide antigens presented on MHC
  2. Co-stimulation signal (B7/CD80)
  3. Cytokines
]]> 2020-05-27 03:33:05 UTC https://padlet.com/190242601/5zlascbmznppzg1v/wish/596069030 Phagosome vs Lysosome vs Endosome 190242601 https://padlet.com/190242601/5zlascbmznppzg1v/wish/596085577 Phagosome - contains a phagocytosed particle enclosed within a part of the cell membrane

Lysosome - contain digestive enzymes to digest excess or worn out organelles, food particles, and engulfed viruses or bacteria

Endosome - sorting and delivery of internalized material from the cell surface and the transport of materials from the Golgi to the lysosome or vacuole]]> 2020-05-27 03:56:35 UTC https://padlet.com/190242601/5zlascbmznppzg1v/wish/596085577 Cross-presentation 190242601 https://padlet.com/190242601/5zlascbmznppzg1v/wish/596090863 Cross-presentation is the ability of certain antigen-presenting cells to take up, process and present extracellular antigens with MHC class I molecules to CD8 T cells]]> 2020-05-27 04:03:56 UTC https://padlet.com/190242601/5zlascbmznppzg1v/wish/596090863 Positive and Negative Selection of T cells 190242601 https://padlet.com/190242601/5zlascbmznppzg1v/wish/596143686 Positive:
- Cells in the thymus present peptides on their own MHC class I and class II molecules which allow immature T cells to bind
- T cells that do not bind undergo apoptosis
- T cell receives survival signals and is positively selected IF a T cell’s TCR successfully binds to the MHC complexes on the thymic cells
-

]]> 2020-05-27 05:14:02 UTC https://padlet.com/190242601/5zlascbmznppzg1v/wish/596143686 How do T cells kill cells ? 19023976 https://padlet.com/190242601/5zlascbmznppzg1v/wish/596543821 TC or CD8 cells are activtated & kills infected cells (or tumour cells) through secretion of perforin and granzymes or activation of the death receptor.]]> 2020-05-27 09:39:11 UTC https://padlet.com/190242601/5zlascbmznppzg1v/wish/596543821 Are T-cells Very Important ? 19023976 https://padlet.com/190242601/5zlascbmznppzg1v/wish/596796248 Helper T cells are important in adaptive immunity, as they are required for almost all adaptive immune responses. Helper T cells help activate B cells to secrete antibodies and macrophages to destroy ingested microbes,, depending on their subtypes. Cytotoxic T cells to kill infected target cells]]> 2020-05-27 12:29:46 UTC https://padlet.com/190242601/5zlascbmznppzg1v/wish/596796248