Laboratory work in the test- tube shows the drugs can inhibit the growth of human cells that are infected with the Aids virus, HIV, and yet leave uninfected cells to grow normally.
The scientists, from Cambridge University, the Royal London Hospital and the Public Health Laboratory Service, believe the results show the drugs could slow the damage caused by HIV and yet be used without causing the severe side-effects of AZT, the commonest anti-Aids drug.
Both drugs, cyclosporin A and FK 506, prevent tissue rejection after transplant operations by inhibiting the body's defences - the immune system. It seems unusual, therefore, that they should inhibit the replication of a virus that also suppresses the immune system.
Abraham Karpas, assistant director of research at Cambridge's Department of Haematology, said: 'What we are able to do is to go some way to explaining this paradox - why an immunosuppressive drug can help in the treatment of an immunosuppressive virus. It seems the drugs, at the dose we used, selectively inhibit the growth of infected cells and not uninfected cells.'
The research, published in the Proceedings of the National Academy of Sciences, shows that infected human blood cells will exhibit a hundredfold reduction in the amount of HIV they produce when grown in the presence of the drugs.
Dr Karpas emphasised that this did not mean a cure for Aids. 'There is no cure in sight. The advantage of cyclosporin A and FK 506 is that they have been given to patients over many years and we know their toxicity.'
Used in conjunction with a treatment whereby blood containing HIV antibodies is transfused into Aids patients, the drugs could prolong life and give a better quality of life, he said.Reuse content