Antibody class switching is an important immunological process allowing B cells to change the type of antibody they produce whilst retaining antigen specificity. It involves for example switching from producing immunoglobulin M (IgM) antibodies, typically the first antibodies produced during an immune response, to other antibody classes such as immunoglobulin G (IgG), immunoglobulin A (IgA), or immunoglobulin E (IgE). Each antibody class has distinct effector functions suited for different types of immune responses. The key enzyme in antibody class switching is Activation-Induced Cytidine Deaminase (AID). AID initiates class switching by deaminating cytidine residues in the switch region DNA of the antibody gene. Deamination results in DNA damage and single-strand breaks that are converted into double-strand breaks (DSBs) by the DNA repair machinery. These DSBs are introduced into the switch regions located upstream of each constant region gene segment for the different antibody classes. The repair of DSBs in the switch regions occurs through the Non-Homologous End Joining (NHEJ) pathway. The switch regions of different antibody classes have repetitive sequences, allowing flexibility in the re-joining of double stranded DNA ends.The repaired DSBs result in a deletion of the DNA between the original constant region and the newly selected constant region. This process determines the class of antibody to be produced. Different cytokines in the B cell microenvironment influence this choice. For example, interleukin-4 (IL-4) promotes switching to IgE, whilst transforming growth factor-beta (TGF-β) and interferon-gamma (IFN-γ) promote IgA switching. In promoting IgE switching, IL-4 signalling activates the STAT6 (Signal Transducer and Activator of Transcription 6) transcription factor which binds to specific DNA sequences in the switch regions of the immunoglobulin heavy chain (IgH) locus. STAT6 binding facilitates the recruitment of co-activator proteins and chromatin remodelling complexes to the IgH locus, increasing gene transcription of the switch regions specific to IgE production. Enhanced transcription of IgE switch regions in turn increases accessibility of these regions to AID which then triggers recombination and deletion of intervening DNA sequences, allowing joining of the constant region of the IgE heavy chain gene. Different antibody classes have distinct effector functions. For instance, IgG antibodies are involved in opsonization, neutralization, and complement activation, whilst IgE is associated with allergic responses. Class switching to IgA is important for mucosal immunity in the respiratory, digestive, and urogenital tracts, where they provide barrier protection. Different antibody classes can also influence the balance of immune responses. IgG subclasses, for example, have varying abilities to activate complement and interact with Fc receptors, modulating the immune response against different pathogens. For example, IgG3 and IgG1 have structural features that make them more effective at activating the complement system, or exhibit higher affinity for Fc receptors, respectively. We offer a large product range of research reagents for studying immunoglobulin class switching, including TdT antibodies, CD40L antibodies, AICDA antibodies, KPNA2 antibodies, and SRP1 antibodies. Explore our full immunoglobulin class switching product range below and discover more, for less.