When harmful bacteria or viruses invade your body, your defense system reacts by producing special molecules called antibodies. These are contained in the globulins. The antibodies kill or neutralize the invaders, which are then eaten by your white blood cells.

What a memory these antibodies have! Scientists earth wide marvel over it. Perhaps as a child you had chicken pox. Even if you have forgotten the disease, your antibodies have not. As long as the antibodies are present and active, you are immune to having the disease again. If a chicken-pox virus invades your body, your antibodies immediately pounce on it. During your life you develop naturally an enormous number of different specific antibodies that protect you from many diseases.

Globulins and antibodies are sometimes used as a treatment when a person has already contracted a disease, such as diphtheria. Instead of taking the risk of allowing the disease to run its course, doctors might recommend accepting a serum prepared from the blood of an animal or human that already contains the right antibodies.a