Haematology, immunology. Blood cells of the immune system derived from the bone marrow and involved in the production of antibodies. B lymphocytes float through all body fluids, are able to detect the presence of foreign invaders, and produce antibodies on their own and when primed by T-lymphocytes. B-lymphocytes can later differentiate into plasma and memory cells. The antigen receptor of the B cells, also called B cell receptor is a immunoglobulin on the surface.