Computer graphics rendering of a cyclosporin molecule. Cyclosporins are a group of biologically active metabolites produced by the fungus Tolypocladium inflatum Gams (formerly known as Trichoderma polysporum). Cyclosporin A may be administered to reduce the risk of tissue rejection that might occur in organ transplants. Cyclosporin A appears to have greater specificity for T-lymphocytes than other cells, that is, it has limited cytotoxicity: many other cytotoxic drugs are effective against all active, dividing cells & have a greater general toxicity.