ABSTRACT
The central component of any immunoassay (IA) is the antibody molecule. Antibodies belong to the family of macromolecules known as immunoglobulins which are present at 12-15 mg/ml in blood serum, amounting to nearly one fifth of its total protein content. Immunoglobulins appear as a very diverse group of proteins, also named globulins. In mammals five immunoglobulin classes (IgG, IgM, IgA, IgD and IgE) with molecular masses ranging from 150,000 to 970,000 Daltons including four IgG (1 to 4) and two IgA (1 and 2) subclasses are known. IgG represents 70% of the serum immunoglobulins and constitutes the majority of the secondary immune response to most antigens.
