Antibodies are generated by immune cells in the body. They work by recognizing surface structures (antigens) of pathogens and attaching themselves to them. Any cells that are flagged in this way are identified by other immune cells as hostile and destroyed. More and more blood cancers can now be treated with artificially produced antibodies — especially non-Hodgkin lymphoma (NHL), but also chronic lymphocytic leukemia (CLL). They work on the basis of a 'lock and key' principle: the available antibodies are the key and work only on cancer cells with a matching lock, or antigen. If lock and key don’t match, the therapy will not work.