Jules Bordet was a Belgian bacteriologist and immunologist who was born in 1870. He studied medicine at the Free University of Brussels and graduated in 1892. In 1919, Bordet received the Nobel Prize in Physiology or Medicine for his discoveries relating to immunity. Through his studies of cholera in 1896, Bordet concluded that there are two types of factors in the blood that fight infection: antibodies formed during immunization against specific bacteria, and complement proteins that exist in non-immunized blood. This established the principle that antibodies and complement proteins work together, a principle still used today in disease testing.