Which aspect of globulins is primarily involved in immunity?

• A. Alpha lipids
• B. Iron
• C. Gamma antibodies
• D. Beta lipids

Answer: (C)

Antibodies, the immune system’s targeted defense molecules, come from the gamma globulin fraction of plasma proteins. When B cells become plasma cells, they secrete immunoglobulins that specifically bind antigens on pathogens or toxins. This binding neutralizes invaders, prevents their entry, and marks them for attack by other immune components. Antibodies can neutralize toxins, cause clumping of microbes, and activate the complement system to destroy or help engulf them. The alpha and beta globulin fractions have other roles, and iron is a mineral, not a globulin. So the immune-related aspect of globulins is the gamma globulin fraction—antibodies.