A type of white blood cell whose function in the adaptive immune system is to secrete antibodies. Additionally, B-cells present antigens and secrete cytokines. In mammals, B-cells mature in the bone marrow. B-cells express B-cell receptors on their cell membrane, which allow the B-cell to bind to a specific antigen, against which it will initiate an antibody response. These cells can create an almost infinite repertoire through recombination and shuffling.