Gamma globulin is one of the classes of proteins found in blood plasma. Gamma globulins play an important role in the body's disease-fighting immune system, and are also known as immune globulins. Most of the antibodies (infection-fighting proteins) in the body fluids are gamma globulins. White blood cells called lymphocytes produce antibodies after coming into contact with such harmful substances as bacteria or viruses. The antibodies react with and help destroy the invading germs.