antibodies
(AN-tih-BOD-eez)
Special fighter proteins made by your immune system. They help protect you from disease. The immune system makes a special protein for each kind of "intruder" that enters the body from the outside. These "intruders" are called antigens. The fighter proteins link up with the antigens like pieces of a puzzle. Once they're linked, the antigen is killed.
Read more about antibodies.
Audio contributed by: Al Roker