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Cystic fibrosis causes the lungs to fill up with thick mucous, leading to constant infections, the need for high doses of antibiotics and high-calorie food, and intensive, daily physiotherapy.

Lisa's lungs were nearly useless when Ron Johnson, a 48-year-old unemployed building-maintenance man from Northamptonshire read about her plight in a London Jewish paper.

He decided to donate a lobe of his lung, as did Lisa's mother — both of them having been found to have compatible tissue.

The operation, performed nearly two months ago, seemed initially to be successful, as Lisa was able to breathe without a respirator and communicate by blinking her eyes. But her condition deteriorated.

She underwent more surgery to stop a hemorrhage and then yet another to cope with an intestinal blockage.

For weeks, she was unconscious and her chances of survival were given as "about 5 percent."

Her parents, who left their healthy daughter Lena at a dormitory school in Kfar Sava, sat at Lisa's bedside, watching her chances for life dwindle and their medical bills mount.

Johnson, who learned of Lisa's death on Saturday, called the educational adviser at the girl's school the next day, saying he was overcome with sadness but wanted to come again to attend the funeral.

"Please console the children for me," he said.

Johnson was in Israel for the first time — and met Lisa's schoolmates — only a few weeks ago, urging them to be strong and believe that she would survive.

His lung capacity has been diminished as a result of his organ donation, and it is not certain he would be regarded as strong enough to get a job.

Many of her classmates went from door to door to try to raise money for her operation.

The children, the Israel Cystic Fibrosis Association and others managed to collect about $450,000.