Understanding the Basics of Memory B Cells—The Antibody Factory
B cells generate humoral immunity by secreting immunoglobulins (Igs; aka antibodies , Abs ) that are specifically selected for high-affinity binding to foreign substances. By 5 or so days after infection or immunization, specific Abs can be detected in serum in the form of IgM heavy chains. [26] Over the next three weeks, Ab levels increase and shift to IgG and IgA heavy chains as antibody affinity increases because of ongoing somatic mutation , reducing the levels of Abs needed for protection. Most IgA Abs are delivered to mucosal surfaces , while IgG Abs typically function in blood, lymph, and tissues . Specific Ab-producing cells persist from weeks to a lifetime depending on the nature of the immunogen . Abs protect against viral infections in many ways: [26] The simplest and typically most effective mechanism is to bind to virion surface proteins and prevent virus attachment to host cells or viral penetration to the cytosol . Th...