Immunotyping is used to detect and identify monoclonal proteins in serum and urine. Serum and urinary proteins are mixed with specific antisera directed against the heavy chains Gamma (IgG), Alpha (IgA), Mu (IgM), and the free and bound light chains kappa (κ) and lambda (λ).

The immunoglobulins react specifically with their corresponding antiserum, and each antiserum profile (IgG, IgA, IgM, κ, and λ) is automatically overlaid with the reference ELP (protein electrophoresis) curve. The disappearance of the anomaly in the profile treated with the antiserum indicates the presence of a monoclonal protein.