Development of human B cells

Stem cells develop into immature and mature B cells. Following appropriate activation, B lymphocytes rearrange their immunoglobulin genes to switch from IgM to IgG, IgA, or IgE. B cells eventually differentiate into plasma cells, which will produce various isotypes of antibodies. When developmental defects occur, immunodeficiency, such as common variable immunodeficiency (CVID), selective IgM deficiency (sIgMD), and selective IgA deficiency (sIgAD) appear.