Which immunoglobulin is primarily responsible for mucosal immunity?

The immunoglobulin that is primarily responsible for mucosal immunity is immunoglobulin A (IgA). IgA is found in high concentrations in mucosal areas such as the gastrointestinal tract, respiratory tract, and urogenital tract, as well as in secretions like saliva, tears, and breast milk. This makes it a critical component of the immune response at mucosal surfaces, where it helps to prevent pathogens from adhering to and penetrating epithelial cells.

IgA functions by neutralizing toxins and pathogens and is crucial in establishing the first line of defense. Its dimeric form, which consists of two IgA monomers linked by a J-chain, is particularly effective in these secretions and enhances its ability to prevent infections at mucosal sites.

Other immunoglobulins, while important in various immune responses, do not play the primary role in mucosal immunity as IgA does. For example, IgG is the predominant antibody in systemic circulation, while IgM is primarily associated with the initial stages of immune response. IgE is mainly involved in allergic reactions and responses to parasitic infections.