Three major classes of plasma proteins are :
(1) Serum albumin, (2) Serum globulin, (3) Fibrinogen. Functions of plasma proteins :
(1) Body immunity : Globulin is associated with the immune response and act as antibodies.
(2) Preventation of blood loss : Fibrinogen which is formed in the liver is necessary for the clotting (coagulation of blood).
(3) Retention of fluid in the blood : Albumin and globulin retains water in blood plasma. Deficiency of protein leads to loss of water from blood to tissue. That's why hands and feet gets swollen (odema).