B Cell Immunity

B cells and the antibodies they secrete are crucial for responding to certain pathogens, as shown by the clinical presentation of patients who lack B cells or antibodies. Such patients show increased susceptibility toward recurrent and/or severe bacterial infections, particularly with encapsulated bacteria. In this chapter, we review basic B cell biology in humans and in mice, including new insights that have been gained recently. Information covered in this chapter includes the types of B cells found in the body, the role of surface receptors in activating B cells, B cell interactions with T cells, formation of germinal centers, isotype switching, affinity maturation, and the production of memory B cells and antibody-secreting plasma cells. Although much has been learned about B cells and how they function in immune responses, questions still remain about the exact mechanisms that control their activation and differentiation programs. Future studies will help to fill in these details and give us a complete picture of how B cells contribute to immunity in response to infectious diseases.