PATHOLOGY

Detailed explanation-1: -T cell activation refers to a process in which mature T cells can express antigen-specific T cell receptors on their surface to recognize their cognate antigens and respond by entering the cell cycle, secreting cytokines or lytic enzymes, and initiating the cell-based functions of the immune system.

Detailed explanation-2: -Killer T-cells find and destroy infected cells that have been turned into virus-making factories. To do this they need to tell the difference between the infected cells and healthy cells with the help of special molecules called antigens. Killer T-cells are able to find the cells with viruses and destroy them.