SOLUBLE INTERLEUKIN-2 RECEPTOR (SIL-2R) LEVELS IN RENAL-TRANSPLANTATION - COMPARISON BETWEEN CLINICAL AND LABORATORY ANALYSIS

Soluble interleukin-2 receptor levels (sIL-2R):were retrospectively ev aluated in 43 consecutive kidney transplant recipients (22 males, 21 f emales), from day 0 up to 90 days after transplantation. 11 pts were o n CsA only, 13 on CsA+MP and 19 on CsA+MP+Aza. All graft-worsening epi sodes were then retrospectively analyzed, either according to clinical criteria only, or taking into account sIL-2R levels. On clinical grou nds, 50 rejections were observed: ''a posteriori'' 5 turned out to be either infections or non-immunological worsenings of graft function (p revalence of misdiagnosis in the rejection set: 5/50, 10%). Of the 8 i nfections, 2 were actually treated as rejections (margin of error: 2/8 , 25%). CsA toxicity was correctly diagnosed in 2/4 episodes. The anal ysis based on sIL-2R levels increase confirmed the clinical diagnosis in 52/79 cases (66%). The prevalence of misdiagnosis was: 21.2% in rej ection, 2/3 in CsA toxicity, while infections were overestimated in 60 % of cases. Isolated sIL-2R level increase was not associated with rej ection in 87.5% of cases,; while an associated increase of IL-2R and p lasma creatinine had a 5% chance of being wrong. SIL-2R levels increas ed before any rise in plasma creatinine in late rejections (28+/-21 da ys after transplantation), while they increased after the rise of plas ma creatinine in early rejections (10+/-5 days) (p=0.014). In the reje ction set, sIL-2R had a sensitivity of 83.4%, a specificity of 80%, a positive predictive value of 50.2% and a negative predictive value of 95.2%. SIL-2R determination does not provide superior results to those obtained with clinical tools (p= 0.15). Nevertheless, sIL-2R may help in predicting rejections occurring later than the 15th post-transplan t day, or in disclosing subclinical episodes of smouldering infection and immunological activation.