How do cytotoxic T cells recognize cells infected with the virus?

When these cells are infected with a virus (or another intracellular pathogen), the cells degrade foreign proteins via antigen processing. These result in peptide fragments, some of which are presented by MHC Class I to the T cell antigen receptor (TCR) on CD8+ T cells.

How does a T cell receptor TCR recognize an antigen?

TCRs recognize an antigen when they bind with major histocompatibility complex (MHC) molecules on the surface of other cells. There are thousands of TCRs on the surface of a T cell, which increases the chances of the T cell binding with an antigen.

What cells recognize MHC?

MHC I are found on all nucleated body cells, and MHC II are found on macrophages, dendritic cells, and B cells (along with MHC I).

How do MHC Class 1 and Class 2 molecules differ in their functions?

MHC genes are expressed to produce surface antigens on the cell membrane. The main difference between MHC class 1 and 2 is that MHC class 1 molecules present antigens to cytotoxic T cells with CD8+ receptors whereas MHC class 2 molecules present antigens to helper T cells with CD4+ receptors.

Why are T cells MHC-restricted?

The biological reason of MHC restriction is to prevent supernumerary wandering lymphocytes generation, hence energy saving and economy of cell-building materials. T-cells are a type of lymphocyte that is significant in the immune system to activate other immune cells.

How do cytotoxic T cells recognize that a cell is infected with a virus and needs to be destroyed?

Cytotoxic T cells have specialised proteins on their surface that help them to recognise virally-infected cells. These proteins are called T cell receptors (TCRs). Each cytotoxic T cell has a TCR that can specifically recognise a particular antigenic peptide bound to an MHC molecule.

What is the main difference between the action of MHC class 1 and MHC Class 2?

The main difference between MHC class 1 and 2 is that MHC class 1 molecules present antigens to cytotoxic T cells with CD8+ receptors whereas MHC class 2 molecules present antigens to helper T cells with CD4+ receptors.

Where do MHC class I molecules bind to peptide antigens?

Class I MHC molecules bind peptides generated mainly from degradation of cytosolic proteins by the proteasome. The MHC I:peptide complex is then inserted via endoplasmic reticulum into the external plasma membrane of the cell. The epitope peptide is bound on extracellular parts of the class I MHC molecule.

What cells recognize MHC II?

MHC II molecules are expressed only on the surface of antigen-presenting cells (macrophages, dendritic cells, and B cells). Antigen presentation with MHC II is essential for the activation of T cells.