Enzyme-linked immunosorbent assay (ELISA) is a biochemical method used to identify the presence of an antibody or antigen in a sample. Human MPF ELISA Kit uses the sandwich ELISA as a method, a highly efficient way of detecting sample antigen. The method involves an unknown amount of antigen being affixed to a surface then a particular antibody is placed on the surface to bind with the antigen. The antibody is linked to an enzyme. With the aid of an added substance, the enzyme converts into some detectable signal, for example, color change.