Simplify the following text for a Grade 9 native English-speaking person.
Original: In response to pathogens some T cells , called T helper cells , produce cytokines that direct the immune response while other T cells , called cytotoxic T cells , produce toxic granules that contain powerful enzymes which induce the death of pathogen infected cells .
Simplified: Other T cells , called cytotoxic T cells , produce toxic granules which cause the death of infected cells .