Immunoglobulin class switching, also referred to as isotype switching or class switching, is a fundamental process in the immune system that allows B cells to change the class of antibodies they produce while maintaining specificity for the same antigen.
Antibodies, also known as immunoglobulins (Ig), play a crucial role in the adaptive immune response. They recognize and bind to specific antigens, initiating the elimination of pathogens or foreign substances. However, different Ig classes have distinct effector functions that are better suited for different types of pathogens or immune responses.
During immunoglobulin class switching, B cells undergo a genetic rearrangement of their antibody-encoding genes. This process involves a recombination event where the DNA sequence between the constant regions of different Ig classes is deleted and replaced, resulting in the production of antibodies with a different constant region. This genetic rearrangement is mediated by specialized enzymes called activation-induced cytidine deaminases (AID).
The ability to switch the immunoglobulin class from IgM to IgG, IgA, or IgE provides enhanced effector functions, such as increased binding to Fc receptors on immune cells, transport across mucosal surfaces, or initiation of inflammatory responses. This process allows the immune system to tailor the antibody response to best combat specific pathogens or respond to different types of infections.
Immunoglobulin class switchings are essential for the establishment of long-term immunity and are crucial in the defense against a wide range of pathogens including bacteria, viruses, and parasites. Failure in class switching can lead to immunodeficiencies, making this process of significant importance in maintaining a functional immune system.
