Which statement describes MHC class I molecules?

MHC class I molecules play a critical role in the immune system by presenting endogenous antigens, primarily derived from proteins synthesized within the cell, to CD8+ cytotoxic T cells. These molecules are expressed on the surface of nearly all nucleated cells, allowing them to inform the immune system about the internal state of the cell, including whether it has been infected by intracellular pathogens such as viruses or has undergone malignancy.

By presenting these internal peptides, MHC class I molecules enable the surveillance capabilities of CD8+ T cells, facilitating the detection and destruction of compromised cells. This widespread expression across all nucleated cells ensures a robust and comprehensive immune response against intracellular threats.

In contrast, MHC class I molecules do not interact exclusively with dendritic cells, nor are they involved solely in extracellular immune responses, which typically involve MHC class II. Additionally, while MHC class I molecules are not the primary interaction partners for natural killer (NK) cells, it is incorrect to say they do not interact at all. NK cells are activated in part by recognizing downregulated or absent MHC class I molecules on target cells, which is a key mechanism by which they identify and kill infected or cancerous cells.

Thus, the statement that MHC class