At the age of 14, James Harrison underwent major chest surgery and he required 13 units (3.4 gallons) of blood afterwards. The blood donations saved his life, and he decided that once he turned 18, he would begin donating blood as regularly as he could.

More than 60 years and almost 1,200 donations later, Harrison retired as a blood donor on May 11. His doctors said it was time to cease the donations — and they certainly don't take them lightly. Harrison's plasma contains an antibody that has saved the lives of 2.4 million babies.

Blood feud

Doctors use Harrison's blood to create anti-D, a treatment for Rhesus disease.

This disease, also called Rh disease or Rhesus D Haemolytic Disease (RHD), is the result of the mother and the fetus having different antigens in their blood. If a mother lacks a D antigen, she is Rh-negative, and this can create a problem if the fetus has the D antigen in its blood. The mother's body treats the blood of the fetus as a foreign invader and attacks with antibodies.

These attacks can result in a range of issues for the fetus, including miscarriages, stillbirths, fatal anemia and even heart failure. This normally occurs in second pregnancies when there is an Rh difference between the mother and the fetus because during the first pregnancy, the mother's body didn't have a strong enough immune response to attack.

Australian scientists realized they could stop these attacks from occurring by injecting Rh-negative mothers with anti-D immunoglobulin, which basically removes the Rh-positive blood cells from the fetus in the mother's blood stream before her body can attack them. The anti-D doesn't pass to the fetus, however, keeping both mother and fetus safe. The video explains in more detail how the system works.

The man with the golden arm

Harrison's blood is valuable because he naturally produces Rh-negative blood, which contains Rh-positive antibodies. His blood has been used to create anti-D in Australia since 1967.

"Every ampule of Anti-D ever made in Australia has James in it," Robyn Barlow, the Rh program coordinator who recruited Harrison, told the Sydney Morning Herald. "Since the very first mother received her dose at Royal Prince Alfred Hospital in 1967."

Harrison was the program's first donor.

"It's an enormous thing ... He has saved millions of babies. I cry just thinking about it."

Since then, Harrison has donated between 500 and 800 milliliters of blood almost every week. He's made 1,162 donations from his right arm and 10 from his left.

"I'd keep going if they let me," Harrison told the Herald. Doctors had already extended the age limit for blood donations for him, and they're cutting him off now to protect his health.

He made his final donation surrounded by some of the mothers and babies his blood helped save.

Harrison's retirement is a blow to the Rh treatment program in Australia. Only 160 donors support the program, and finding new donors has proven to be difficult. Additionally, attempts to create a synthetic version of anti-D have failed.

But just because Harrison has retired from giving blood doesn't mean he's completely out of the game. Scientists are collecting and cataloging his DNA to create a library of antibodies and white blood cells that could be the future of the anti-D program in Australia.

This man's blood has saved 2.4 million babies
James Harrison's plasma is used to make treatments for Rhesus disease. He has made 1,173 donations over more than 60 years, but now he has to retire.