Question

CD4 and CD 8 are _______. A. proteins secreted by antigen-presenting cells B. receptors present on the surface of natural killer cells C. molecules present on the surface of T cells where they interact with major histocompatibility (MHC) Molecules D. molecules on the surface of antigen-presenting cells where they enhance B cell activity

Answer 1

CD4 and CD 8 are molecules present on the surface of T cells where they interact with major histocompatibility (MHC) Molecules.

CD4 and CD8 improve T cell signalling by attaching to MHC class II (CD4) or MHC class I (CD8) molecules on APCs.

• The association of CD4 with MHC class II significantly decreases the number of antigenic peptides necessary for T cell activation (5) and significantly boosts cytokine output by helper T cells.

The MHC molecules' wide polymorphism is their distinguishing trait.

• This polymorphism is crucial for T cell antigen recognition.
• A T cell detects antigen as a peptide bound by a specific allelic variation of an MHC molecule and will not identify the identical peptide bound by other MHC molecules.
• This type of T cell activity is known as MHC limitation.

Hence, the correct answer is option C

Learn more about MHC here,

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