If you suspect major deficiency of antibodies in a person, to which...

Chemically, antibodies are globular proteins, belong to a class of serum proteins, which are called $\gamma$ or gamma globulins. Thus, the antibodies are also known as immunoglobulins and are produced by the lymphocytes. Hence, to confirm the deficiency of antibodies in a person, serum globulins will be tested. Related Theory Blood proteins, also termed plasma proteins, are proteins present in blood plasma. 90-92 per cent of plasma is water and proteins contribute 6-8 per cent of it. Fibrinogen, globulins and albumins are the major proteins. Fibrinogens are needed for clotting or coagulation of blood. Globulins primarily are involved in defense mechanisms of the body and the albumins help in osmotic balance.