SEQUENTIAL MONITORING OF URINE-SOLUBLE INTERLEUKIN-2 RECEPTOR AND INTERLEUKIN-6 PREDICTS ACUTE REJECTION OF HUMAN RENAL-ALLOGRAFTS BEFORE CLINICAL OR LABORATORY SIGNS OF RENAL DYSFUNCTION

Background. The significance of noninvasive techniques to the early di agnosis of acute rejection in kidney transplants remains elusive. In t his study, we examined whether an early posttransplant increase in ser um- and urine-soluble interleukin (IL) 2 receptor (sIL-2E) and IL-6 le vels predicted acute rejection. Methods. Sequential determinations of serum and urine sIL-2R and IL-6 were performed in the first 30 postope rative days in 40 renal transplant patients. Changes during the posttr ansplant period observed in 26 patients who had one or more episodes o f acute rejection (group A) were compared with those recorded in 14 pa tients who did not experience acute rejection of their graft (group B) . Results. Serum sIL-2R was higher than normal in patients of groups A and B without statistical differences between the two groups. In the first 3 days after transplantation, urinary sIL-2R was higher than nor mal in group A but not in group B. Urinary sIL-2R at days 2 and 3 was significantly higher (P<0.05) in group A than in group B. In the first 5 days after transplantation, urinary IL-6 was persistently higher th an normal in group A, whereas it progressively decreased to normal val ue on day 4 in group B. Sudden increases (doubling within 24 hr) in ur ine IL-6 preceded clinical diagnosis of acute rejection by a mean peri od of 2 days, with an 87% sensitivity and a 64% specificity, and also predicted recurrent rejection episodes. Conclusions. Sequential monito ring of urinary sIL-2R and IL-6 levels does allow very early diagnosis of rejection without invasive procedures. Specifically, high urinary sIL-2R in the first 5 posttransplant days identifies the subgroup of p atients at risk. In the subsequent days, a sudden increase in urinary IL-6 occurs in those of the above patients who will indeed reject thei r graft.