sentence: Cytokines signal to other immune cells that there is a foreign antigen present.
sentences_before: Some T cells, called T helper cells, produce cytokines that direct the immune response.
sentences_after: Other T cells, called cytotoxic T cells, produce toxic granules which cause the death of infected cells.
concept_name: cytokine
headings: Lymphocyte Types T and B cells
categories: Cell biology Immunology Blood cells