Stephen Crohn, previously dubbed “The Man Who Can’t Catch AIDS” because of his resistance to HIV, has committed suicide, aged 66.

Crohn’s boyfriend, Jerry Green, a gymnast, was among the first people to die of AIDS in 1982 after contracting HIV in 1978.

Crohn’s resistance helped lead to a deeper understanding of HIV.

He volunteered to have his white blood cells exposed to HIV but doctors were unable to infect him – even at concentrations thousands of times stronger than anything that would occur outside of a laboratory setting.

The CD4 white blood cells, which HIV normally penetrates to start the process of disease, locked out the virus.

Years later they found out the reason why: HIV gets into the white blood cells by fitting into two receptors but Crohn’s second receptor was flawed due to a genetic defect.

The anomaly found in less than 1% of the population saved Crohn’s life.

“What he contributed to medical knowledge is really quite extraordinary,” said Dr Bruce D Walker, director of the Ragon Institute of Massachusetts General Hospital, MIT and Harvard.

In 1996, The Independent called Crohn “The Man Who Can’t Catch AIDS,” and he told his story in documentary films and newspaper interviews around the world.

It was announced last Friday that Crohn had committed suicide on 23 August.

The New York Times reports his sister, Amy Crohn Santagata, said: “My brother saw all his friends around him dying, and he didn’t die.

“He went through a tremendous amount of survivor guilt about that and said to himself, ‘There’s got to be a reason.”‘

She added: “He was quite extraordinary, and then also quite ordinary.”