CD8 is a marker primarily for which lymphocyte subset?

CD8 is a marker primarily for which lymphocyte subset?

• A. B cells
• B. T helper cells
• C. Cytotoxic T cells
• D. Regulatory T cells

Answer: (C)

CD8 marks cytotoxic T lymphocytes, the subset of T cells responsible for directly killing infected or abnormal cells. The CD8 molecule acts as a co-receptor that binds to MHC class I molecules on nearly all nucleated cells, strengthening the T cell receptor's recognition of peptide antigens presented by those cells and promoting the cytotoxic response with mechanisms like perforin and granzyme release. B cells carry markers such as CD19 and CD20, not CD8. T helper cells typically express CD4, and regulatory T cells are a subset of CD4+ T cells characterized by FOXP3 expression, not CD8.

CD8 marks cytotoxic T lymphocytes, the subset of T cells responsible for directly killing infected or abnormal cells. The CD8 molecule acts as a co-receptor that binds to MHC class I molecules on nearly all nucleated cells, strengthening the T cell receptor's recognition of peptide antigens presented by those cells and promoting the cytotoxic response with mechanisms like perforin and granzyme release.

B cells carry markers such as CD19 and CD20, not CD8. T helper cells typically express CD4, and regulatory T cells are a subset of CD4+ T cells characterized by FOXP3 expression, not CD8.