Cyclosporine

How it works

Made by a soil fungus, this ring of 11 amino acids reins in T cells, the immune cells that reject a transplanted kidney or heart.

What it's made of

11 amino acids closed in a ring, several of them rare ones our proteins do not use. It does not come from a gene: the enzymes of a soil fungus assemble it. The drug is the fungus's molecule, unchanged.

What it's for

Prescribed for

Preventing rejection of transplanted kidney, liver and heart; severe rheumatoid arthritis and psoriasis. As eye drops, dry eye with inflammation that reduces tears.