Which type of cells express the CD8 marker?

Cytotoxic T Cells are characterized by the expression of the CD8 surface marker, which is critical for their function in the immune system. CD8 is a co-receptor that enhances the interaction between the cytotoxic T Cells and MHC Class I molecules, facilitating the recognition and elimination of infected or malignant cells. This interaction is vital for the ability of cytotoxic T Cells to kill target cells effectively.

Natural Killer Cells, while also involved in the immune response and recognized for eliminating infected or cancerous cells, do not express the CD8 marker; instead, they have their distinct set of activating receptors. B Cells primarily express different markers such as CD19 and CD20, playing a key role in antibody production. T helper Cells express the CD4 marker rather than CD8, which is fundamental in immune regulation and activation of other immune cells. Thus, the specific expression of CD8 is a defining feature of Cytotoxic T Cells, distinguishing them within the immune system.