In 1981, 80 years after Karl Landsteiner phlebotomized his own blood to prove the existence of blood types, another self-experimenting physician, Dr. Jack Goldstein, furthered the field of blood type. In doing so, he managed to expand the pool of available donors for people with type O blood in need of blood transfusions. This was an important moment in the field; although people with type O blood could give blood to anyone, they could only receive type O blood themselves.
Goldstein discovered that an enzyme found in coffee, alpha-galactosidase, could render the antigens in B-type blood harmless. This chemical reaction effectively transformed B-type blood into what resembled O-type blood. If transfused into O-recipients, it would expand the available donors for B-type as well.
Since Goldstein had type O blood, he underwent a blood transfusion of type B red blood cells that had been treated with the enzyme, rendering it into type O blood. Having received the transfusion without an adverse reaction, Goldstein showed that the technique worked [source: Altman].