<qa>  What is the name of the T lymphocytes that can kill viral cells?T lymphocytes can kill viral cells but normally there are not enough of them to kill all the virus infected cells after transplant. Some researcher have taken T cells from a persons blood, grown more of them in the laboratory and then given them back to the person during a viral infection after a bone marrow transplant. Some of these studies have shown a positive therapeutic effect in patients receiving the CTLs after a viral infection in the post-transplant period. 