Blood type group systems, 308 different blood-group antigens have been found. Almost always, an individual has the same blood group for life, but very rarely an individual's blood type changes through addition or suppression of an antigen in infection, malignancy, or autoimmune disease. Another more common cause in blood type change is a bone marrow transplant. Bone-marrow transplants are performed for many leukemias and lymphomas, among other diseases. If a person receives bone marrow from someone who is a different ABO type (e.g., a type A patient receives a type O bone marrow), the patient's blood type will eventually convert to the
Blood type or anti-B antibodies. Typically, blood type tests are performed through addition of a blood sample to a solution containing antibodies corresponding to each antigen. The presence of an antigen on the surface of the blood cells is indicated by agglutination. An alternative system for blood type determination involving no antibodies was developed in 2017 at Imperial College London which makes use of paramagnetic molecularly imprinted polymer nanoparticles with affinity for specific blood antigens. In these tests, rather than agglutination, a positive result is indicated by decolorization as red blood cells which bind to the nanoparticles are pulled toward a magnet