Cytotoxic T lymphocytes (CTLs) constitute a subset of T lymphocytes that secrete various cytokines to participate in immune responses. Together with natural killer cells, they form a crucial defense line in the body's antiviral and antitumor immunity. This kit is designed for the efficient in vitro expansion of CTLs from mononuclear cells (MNCs). The expanded CTLs (CD3+CD8+) achieve approximately 80% purity, providing a valuable tool for immunological research. The kit features well-defined components free of heterologous elements; it is sterile, mycoplasma-free, and low in endotoxins. It is equally suitable for use with both umbilical cord blood and peripheral blood.