B-cell, colored scanning electron micrograph - stock illustration

B-cell, coloured scanning electron micrograph (SEM). B-cells are a type of white blood cell involved in immune respone. They account for 10 per cent of the body's lymphocytes. On encountering a foreign antigen, such as a bacterial surface protein, the immature B-cell either divides into a number of plasma cells, which produce antibodies, or it matures into a memory cell. Memory cells remain in the body for years, giving immunity to the original pathogen. The cell surface is covered with microvilli, to help it bind to target proteins. Magnification: x6000 when printed at 10 centimetres wide.