T-cells and lung cancer cell. Composite coloured scanning electron micrograph (SEM) of T-cells (red) and an adenocarcinoma lung cancer cell. T-cells are a component of the body's immune system. CAR T-cell therapy takes T-cells from a cancer patient's blood and modifies them to recognize a specific protein found on patient's tumor cells. When reintroduced to the patient the T-cells find and destroy the tumour cells. The newest form of CAR T-cell therapy, now in clinical trials, uses "memory" T-cells which remain in the body after attacking the cancer. The hope is that memory T-cells may provide an active reservoir of cancer-killing cells capable of stopping further tumours. Magnification: x2000 at 10cm wide. Specimen courtesy of Professor Greg Towers, University College London, UK