B-cell biology.

B-lymphocyte functions can be divided broadly into antigen presentation and production of antibodies. Defects in either of these functions may lead to immunodeficiency or autoimmunity. For the rheumatologist, it is important to understand B-cell development, maturation, and activation to fully comprehend how alterations in these processes shape the B-cell repertoire and can lead eventually to autoimmunity and organ pathology. The goal of this article is to demonstrate how small changes in the selection of the B-cell repertoire, can, over time, and with the necessary environmental influences, lead to rheumatic disease.