Immunoglobulins or specific antibodies or gamma globulins are blood proteins, which are found to be defensive only against the specific microorganisms, or their toxins that evoked that particular antibody. Immunoglobulins are glycoproteins, made up of 4 polypeptide chains (linked by disulphide bonds). There are two long chains, called heavy or H chains, and two short chains, called light or L chains. The four polypeptide chains are held together to form Y shaped molecule. The top two tips of this shaped molecule bind to the specific antigens in a lock and key fashion, forming an antigen antibody complex.