IgM

Immunoglobulins are an important part of the body’s immune response. The immunoglobulin M (IgM) molecule is composed of a pentamer of two light chains (kappa and lambda) and the two mu heavy chains plus a J chain. IgM is the largest immunoglobulin molecule, MW = 900,000 daltons. It makes up approximately 6% of the total immunoglobulin. IgM is the body’s primary immune response. The level of IgM in serum increases in hepatic disease, and bacterial or viral infections. The levels of IgM decrease with congenital immunodeficiency. The measurement of IgM provides useful information in the assessment of these diseases or conditions.