Cyclosporin A--usefulness, risks and mechanism of action.

TLDR: A review of the present state of knowledge on cyclosporin A is warranted because the drug has already been admirably analyzed in these reviews, but much relevant information on it has accumulated since then.

Abstract: Very little new happened in the field of immunosuppression after the discovery of azathioprine in the early 'sixties (Schwarz et al. 1959). Admittedly, there has been the introduction of heterologous antilymphocyte serum (Starzl et al. 1967), which to some extent has become a part of the regular therapeutic regimen in organ transplantation. Other than that, very little that could stop an immune response has been brought forward by the immunologists during these two past decades. Nevertheless, the understanding of immune functions has advanced a great deal during that same period, although in terms of immunosuppression the transplant surgeons were left with the old, but not so effective combination of steroids, azathoprine and somewhat later anti-lymphocyte serum (that, indeed, they still use). But a new drug is rapidly invading the market. That is cyclosporin A (CyA), which is the scope of this review. Although it was detected nearly 10 years ago (Borel 1976), it is still new as it is presently being scrutinized in clinical trials in man and is thus not commonly in use yet. In most countries it has as yet only been used for very limited purposes. The attraction of this compound is multifold, but one feature is that, unlike all other immunosuppressants, tentative mechanisms of action for it have been brought forward based on interpretable experimental data. This is, we think, why a review of the present state of knowledge on cyclosporin A is warranted. The drug has already been admirably analyzed in these reviews (Calne 1979), but much relevant information on it has accumulated since then.