Alpha 2-Macroglobulin (A2M) is a major protease inhibitor in serum and an acute phase protein which increases significantly in concentration in the rat as a result of inflammation. The major pathophysiological role for rat alpha 2-macroglobulin has yet to be conclusively defined. This kit is specific to the alpha 2- macroglobulin and will not cross react with the closely related alpha 1-macroglobulin.