Scientists found powerful medicines that help with kidney transplants by looking at dirt - specifically, germs in the soil that led to drugs like cyclosporine, tacrolimus, and rapamycin.

The study tells the story of how rapamycin was discovered from a soil sample from Easter Island and is now used to prevent organ rejection. This supports part of the claim about soil samples leading to immunosuppressant discoveries, though it only covers one of the three drugs mentioned.