Illustration of chimeric antigen receptor (CAR) T cells (blue) attacking non-Hodgkins lymphoma cells (purple). Lymphoma is a malignant (cancerous) growth of white blood cells (lymphocytes). White blood cells are part of the bodys immune system and circulate in a clear liquid called lymph. There are many types of lymphoma depending on the cells affected. All lymphomas however, are divided into 2 types, Hodgkins lymphoma and non-Hodgkins lymphomas. Hodgkins lymphoma is characterised by the presence of Reed-Sternburg cells, a giant type of macrophage. All other lymphomas are non-Hodgkins. The cause of lymphomas are not known. CAR-T therapy is a type of immunotherapy that genetically modifies a patients own T cells, a form of white blood cell, to recognise and destroy cancer cells.