(CNN) Charlie Ball and Kenneth Walker went to school together more than 50 years ago and now live on opposite coasts. But despite the time and distance between them, the two are now sharing more than high school memories.

Walker and Ball are alumni of Archbishop Carroll High School in Washington, D.C. Even though they both graduated in 1969, the two never really spoke to one another. But when Walker sent out an email last year to his old classmates asking for a kidney, Ball said he recognized the name.

He decided to respond. If he was a match, he told Walker, he would donate his kidney.

"Understandably, I think no one I've spoken to would do this," Ball told CNN from the hospital after the surgery. "It depends on the person, I guess."

It only took a few months to set everything up. The classmates reunited in Washington, DC, where Walker still lives. In March, they attended a dinner with about 20 classmates, reminiscing and making up for lost time. Then, this week, they walked into George Washington University Hospital to undergo the life-saving procedure.

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