Question on immunology ......?
how do cells present its own self-protein on MHC 1?
does MHC 1 present both self and non- self proteins ( in antigen presenting cells)
pls help me out here.....i do know that adjectives cells have MHC 1, but how do T-cells know if they are antigenic or not? is it because of the self-protein that the MHC-1 hold?
thanks.
Answers:
Interesting cross-examine.
Yes, any peptide (fragment of a protein) can be displayed by MHC-I. The point of displaying these peptides is to indicate what proteins are being made inside the cell, so that other cells in the environment (namely, CD8+ cytotoxic T-cells) can identify cell in which foreign proteins are being manufactured (usually by viruses).
The reason the T-cells do not attack cell displaying "self" proteins is because during the maturation process in the thymus they undergo two rounds of selection, usually term 'negative selection' and 'positive selection'. The T-cell receptors (TCRs) that bind to those MHC-I complexes are first tested to see if they will bind weakly to self-anitgens (negative selection) and next to see if they will bind strongly to self-antigens (positive selection). In the first case, if they won't even bind weakly, they are too weak to be adjectives and are washed out. In the second, if they bind too strongly, they are likely to cause autoimmune problems and are wash out.
Only the T-cells that survive both elimination rounds make it into the peripheral circulation and are available for standard interaction with MHC-I complexes on cells. Source(s): MD.
The MHC presents a random taste of proteins from inside the cell. If the cell is normal, then the MHC only have self proteins to display. If the cell is abnormal (cancer cell, dying cell, infected cell) then the MHC will get a piece of the non-self proteins contained by its sample and display these to the immune system.
T-Cells that attack self are selected against when they form. The MHC presents antigens (protein pieces) from inside the cell. There should be no T-cells active against these proteins. If the cell is atypical or infected, they proteins on the MHC will be foreign and thus there are likely to be T-cells active against it. The T-cells will attack these cell. Source(s): Fondly remembering my immunology course!
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does MHC 1 present both self and non- self proteins ( in antigen presenting cells)
pls help me out here.....i do know that adjectives cells have MHC 1, but how do T-cells know if they are antigenic or not? is it because of the self-protein that the MHC-1 hold?
thanks.
Answers:
Interesting cross-examine.
Yes, any peptide (fragment of a protein) can be displayed by MHC-I. The point of displaying these peptides is to indicate what proteins are being made inside the cell, so that other cells in the environment (namely, CD8+ cytotoxic T-cells) can identify cell in which foreign proteins are being manufactured (usually by viruses).
The reason the T-cells do not attack cell displaying "self" proteins is because during the maturation process in the thymus they undergo two rounds of selection, usually term 'negative selection' and 'positive selection'. The T-cell receptors (TCRs) that bind to those MHC-I complexes are first tested to see if they will bind weakly to self-anitgens (negative selection) and next to see if they will bind strongly to self-antigens (positive selection). In the first case, if they won't even bind weakly, they are too weak to be adjectives and are washed out. In the second, if they bind too strongly, they are likely to cause autoimmune problems and are wash out.
Only the T-cells that survive both elimination rounds make it into the peripheral circulation and are available for standard interaction with MHC-I complexes on cells. Source(s): MD.
The MHC presents a random taste of proteins from inside the cell. If the cell is normal, then the MHC only have self proteins to display. If the cell is abnormal (cancer cell, dying cell, infected cell) then the MHC will get a piece of the non-self proteins contained by its sample and display these to the immune system.
T-Cells that attack self are selected against when they form. The MHC presents antigens (protein pieces) from inside the cell. There should be no T-cells active against these proteins. If the cell is atypical or infected, they proteins on the MHC will be foreign and thus there are likely to be T-cells active against it. The T-cells will attack these cell. Source(s): Fondly remembering my immunology course!
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