Early graft function.

1. The average serum creatinine level during the first 20 days after transplantation was lower in HLA-identical siblings than in parental donor transplants, suggesting an early effect of histocompatibility. 2. In rather small numbers of patients, the daily average serum creatinine values were not different with HLA-DR mismatching and HLA-B,DR mismatching, but were lower in the better matched transplants for the HLA-A,B loci and the HLA-A,B,DR loci. 3. The average serum creatinine values in the first 20 days after transplantation were correlated with the one-year graft survival rates. Those patients with serum creatinine levels less than 2.4 mg/dl had one-year graft survival rates of over 80% compared with those with serum creatinine levels above 7.5 mg/dl after the first week who had one-year graft survival rates about 30% less. Intermediate serum creatinine values yielded intermediate one-year graft survival rates. 4. The cyclosporine dosage in the first month after transplantation varied considerably among the four centers studied here. These values were not directly correlated with the one-year graft survival rate, average serum creatinine levels or cumulative rejection rates in this preliminary examination. 5. Patients who rejected transplants 11 to 60 days posttransplant had been given lower cyclosporine dosages than those who rejected early or who had no rejections. 6. Although firm conclusions cannot be drawn from the small numbers of patients encompassed in this study, we hope the potential value of this type of analysis will be realized.