Antibody, CAR and TCR structures, illustration. At left is the antibody immunoglobulin G (IgG). This Y-shaped protein is produced by B-lymphocyte white blood cells as part of an immune response to fight off infections. At centre is a chimeric antigen receptor (CAR), an engineered cell receptor that allows T cells to recognize and attack cancer cells in a specific way. At right, a T cell receptor (TCR, similar to one arm of an antibody) activates the immune response to antigens in T cells (a form of lymphocyte).