Immunoglobulins (Ig) are critical components of the immune system and play a major role in eliciting the body's immune response against pathogens. Five heavy-chain isotypes (IgA, IgD, IgE, IgG, and IgM) mediate specific biological functions, including responses to pathogens and immunological diseases such as allergies and autoimmune disorders. IgA has two subclasses (IgA1 and IgA2) and exists in both monomeric and dimeric forms. It is approximately 15% of the total serum Ig content. Secretory IgA is a dimer that provides the primary defense against localized infections. High levels of IgA are often found in samples associated with chronic infections such as cirrhotic liver disease. This kit provides the assay-specific components for the quantitative determination of IgA in human, cynomolgus monkey, and rhesus monkey sera samples.