Curious George

Yael:I just read about an exciting technique.Researchers found a way to convert types A and B blood into type O blood--the type that can be transfused into any patient.This advance could help avoid blood shortages in the future.

Don:Wow,that is exciting.But what makes type O blood so special?

Y:Blood types result from different carbohydrates,called antigens,on the surface of human blood cells.Your blood "type"denotes the kinds of antigens you have on the surface of your cells.People with type A blood have A antigens;those with type B have B antigens.If you have both kinds of antigens,you're type AB;if you have neither one,you're type O.

Your immune system recognizes the antigens on your blood as "self",but attack cells with "foreign"antigens.So if you ever need a blood transfusion,it's important that you only receive blood compatible with your own type.

D:I see.So if a type A person receives type B or AB blood,her immune system will see the B-antigens as foreign,and attack the donor blood cells?

Y:Exactly.But type O is called the "universal donor"since it doesn't have any antigens that would set off the body's defense system.

A team of Danish scientists has identified enzymes that remove the A and B antigens from blood cells.The enzymes,which were extracted from a bacteria and a fungus,essentially change any donated blood into type O.

Clinical trials are underway to test whether the treated blood is safe and effective.If so,the technology could help save lives,since type O blood is such a precious commodity