Childhood nephrotic syndrome (NS) is frequently characterized by a relapsing course. There is no uniform agreement about the precise stage at which a steroid-sparing agent should be introduced to control the disease. In order to evaluate the treatment strategies and outcome of steroid-sensitive NS over the last 2 decades, a retrospective notes review was undertaken in a cohort of children treated at Great Ormond Street Children's Hospital between 1980 and 2000. From a population of 863 children with NS referred, 509 had frequently relapsing or steroid-dependent disease and 261 children received at least one steroid-sparing agent. Cyclophosphamide was the first choice in 178 patients and in 114 no further steroid-sparing agent was needed. Levamisole was prescribed as the first steroid-sparing agent for 65 children and disease control was achieved in 30%. Cyclosporin A was prescribed in 61 children and sustained remission was induced in 69%. It is concluded that cyclophosphamide is a potent agent in inducing sustained remission in steroid-sensitive NS. Levamisole and cyclosporin A have emerged as attractive steroid-sparing agents. Complications and major side effects of treatment are infrequent but occasionally fatal.
Robert Schwartz investigated the effect of 6-MP on the immune response in 1958 and discovered that it profoundly suppresses the formation of antibodies when given to rabbits together with antigens .  Following the work done by Sir Peter Medawar and Gertrude Elion in discovering the immunological basis of rejection of transplanted tissues and organs, and Schwartz's researches on 6-MP, Sir Roy Calne , the British pioneer in transplantation, introduced 6-MP as an experimental immunosuppressant for kidney and heart transplants .  When Calne asked Elion for related compounds to investigate, she suggested azathioprine, which was subsequently found out to be superior (as effective and less toxic to the bone marrow) by Calne.   On 5 April 1962, with regimens consisting of azathioprine and prednisone , the transplantation of kidneys to unrelated recipients (allotransplantation) was successful for the first time.   For many years, this kind of dual therapy with azathioprine and glucocorticoids was the standard antirejection regimen, until ciclosporin was introduced into clinical practice (by Calne as well) in 1978.