A fungus from Norwegian soil made organ transplants far safer

Drug companies routinely screened soil fungi for new antibiotics, hoping to find the next penicillin. A sample collected on a Norwegian plateau in 1969 held a fungus that made a compound nobody expected, one that calmed the immune system instead of killing bacteria.

Researchers at Sandoz in Switzerland tested the compound, cyclosporine, in mice and found it suppressed the specific immune cells that attack transplanted tissue without wiping out the rest of the immune system the way older drugs did. That selectivity later made transplants far more likely to succeed.

Kidney, liver, and heart transplant survival rates rose sharply after cyclosporine reached the clinic in the early 1980s, and it remains a standard anti-rejection drug today alongside newer options with fewer side effects. The fungus that produced it has since been found in soil on several continents, not only Norway.

A soil sample made transplants ordinary.