Cytotoxic t-lymphocytes produce a substance called

Cytotoxic T lymphocytes make a substance called perforins,granzymes, FasL

Explanation:

Cytotoxic T lymphocytes (CD8 +) recognize infected cells and destroy them by secreting molecules that activate apoptosis of the target cell (substances such as perforins, granzymes, FasL)

chemical changes occur when a substance combines with another to form a new substance, called chemical synthesis or, alternatively, chemical decomposition into two or more different substances. these processes are called chemical reactions and, in general, are not reversible except by further chemical reactions. some reactions produce heat and are called exothermic reactions and others may require heat to enable the reaction to occur, which are called endothermic reactions. understanding chemical changes is a major part of the science of chemistry.