T lymphocyte and lymphoma cancer cell. Coloured scanning electron micrograph (SEM) of a T lymphocyte cell (blue/ purple) attached to a lymphoma cancer cell. Lymphoma is cancer that starts in the lymph glands or other organs of the lymphatic system. There are many different types and the treatment varies for the different types. T lymphocytes are a type of white blood cell that recognise a specific site (antigen) on the surface of cancer cells or pathogens and bind to it. Some T lymphocytes then signal for other immune system cells to eliminate the cell. The genetic changes that cause a cell to become cancerous lead to the presentation of tumour antigens on the cell's surface. Magnification: x6000 when printed at 10 centimetres wide.