True about IgM is: September 2005

Ans. B: Primary response IgM is the immediate antibody that is produced once a human body is exposed to bacteria, virus or a toxin.Their demonstration in the serum indicates recent infections. IgG is found throughout the body, mainly in most of the bodily fluids, while IgM is found mainly in the blood and lymphatic fluids. Antibodies formed in primary response are predominantly IgM and in the secondary response is IgG. IgM is temporary and disappears after a few weeks. It is then replaced by IgG.