Antitumor activity is shown by all except -

Ananthanarayanan and Paniker's textbook of microbiology 9th edition. cytotoxic T cells can kill and lyse target cells carrying new or foreign antigens including tumor,allograft and virus infected cells. Natural killer cells are natural defence against virus infected and malignant mutant cells. activated macrophages secrete a number of biologically active substances including hydrolytic enzymes , TNF , Colony stimulating factor and IL 1. This they have tumor cytotoxicity..