What is the main antibody in mucus?

The main antibody found in mucus is immunoglobulin A (IgA). This antibody plays a crucial role in the immune defense of mucosal surfaces, which includes the respiratory and gastrointestinal tracts. IgA is secreted in high concentrations in mucosal areas and provides protection by preventing pathogens from adhering to epithelial cells and facilitating their removal.

In the context of mucosal immunity, IgA can exist in two forms: serum IgA (monomeric) and secretory IgA (dimeric). The secretory form is particularly important as it is specifically adapted to function in mucous secretions, providing a first line of defense against infections. This function is vital as it helps maintain the health of mucosal surfaces, where pathogens commonly invade.

The other antibody types mentioned serve different roles in the immune response. For example, IgE is primarily involved in allergic responses and protection against parasitic infections; IgM is mainly involved in the initial response to infections; and IgG is the most abundant antibody in serum, playing a key role in systemic immunity but is not prominently present in mucus. Thus, the significance of IgA in mucosal immunity highlights its role as the main antibody in mucus.