The rare documents will be auctioned by Henry Aldridge & Son on Feb. 24.
The three letters from Diana and her lady-in-waiting were sent to the friend of an AIDS victim who had contacted the Princess requesting help. Margaret Bendon contacted Diana in July 1996 on behalf of Vincent Hickey, who had AIDS and bowel cancer.
The correspondence documents the Princess’s efforts to help Hickey – she sent a check for £580 ($812) to enable Hickey and Bendon to visit the Catholic shrine of Lourdes in Southern France.
In a typed letter dated Oct. 3, 1996, the Princess thanks Bendon for the gift of a small medal following their trip to Lourdes. “I was most touched to receive your very kind letter about your visit to Lourdes with Vincent,” she wrote. “I was delighted to be able to help and so glad that he was well enough to travel.”
“It is so important that every bit of comfort is given to people like Vincent who, as you know, need all the care and help we can give them,” she added. The letter is signed “with love from Diana.”
Princess Diana, who was famed for her charitable work, died in August 1997 after sustaining fatal injuries in a Paris car crash. She was 36.
"[The letters] demonstrate the empathy and generosity Diana was able to show to some of the more vulnerable members [of] society and just illustrate what an incredible person she was," auctioneer Andrew Aldridge told Fox News.
The lot has a pre-sale estimate of £2,000-3,000 ($2,802-$4,202).
Last year ,letters sent by Princess Diana to a Buckingham Palace official, including one revealing that Prince Harry was "constantly in trouble" at boarding school, sold at auctionfor thousands of dollars.
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