B cells and helper T cells recognize antigens on pathogens that are free-floating between cells. When a B cell and a helper T cell recognize the same antigen, the T cell can activate the B cell to divide and become plasma cells. Plasma cells secrete antibodies that bind specifically to antigens on pathogens to inactivate and destroy them. Specific memory B cells are also produced and spring into action if the same pathogen is encountered again in the future.