FluoroSpot Flex: Mouse IgG/IgA

Immunoglobulin G (IgG) is the most abundant Ig isotype in serum, making up approximately 80% of all serum immunoglobulins. In humans, there are four subclasses of immunoglobulin G, with the highest serum concentrations of IgG1 followed by IgG2, IgG3, and IgG4. In mice, the IgG subclasses are defined as IgG1, IgG2a/c, IgG2b, and IgG3. The IgG molecule consists of two heavy and two light chains (κ or λ), resulting in a molecule with two arms for antigen binding. High levels of IgG antibodies are induced following the initial IgM response in a typical immune response to antigens.

IgA (Immunoglobulin A) represents only 10-15% of the total Ig molecules in serum but is the predominating Ig isotype in secretions and in the gastrointestinal and urogenital tract. The IgA found in secretions (secretory IgA or sIgA) is commonly a dimer with two IgA molecules joined by the J chain. Secretory IgA is the most important Ig isotype in mucous surfaces, the area of entry for most pathogens.