Immunoglobulin G (IgG) is a type of antibody. IgG is the most common type of antibody found in blood circulation. IgG molecules are created and released by plasma B cells. In mice, the IgG class is further divided into four subclasses: IgG1, IgG2a/ IgG2c (strain specific), IgG2b, and IgG3. The mean serum Ig levels found for 6-month-old B6 mice were 0.22 mg/ml for IgM, 0.28 mg/ml for IgG1, 1.22 mg/ml for IgG2b, 0.18 mg/ml for IgG3, 0.075 mg/ml for IgA and about 0.7 mg/ml for IgG2a. This kit is for the quantitative measurement of mouse total IgG in mouse serum, plasma and supernatant from cell cultures.