Background: S100B is a prominent cell damage marker which can lead to sustained pro-inflammatory signaling. The aim was to investigate cross-sectional associations of steady-state S100B concentrations, particularly with C-reactive protein (CRP), in renal transplant recipients (RTRs) and also to investigate prospectively whether S100B would predict graft failure or mortality.
Material/Methods: Outpatient RTRs with a graft functioning for >1 year were eligible for participation in this study. S100B was determined at baseline from serum. Mortality and the occurrence of graft failure were recorded until September 2007. Multivariable linear regression analyses were performed to identify potential determinants of S100B. Multivariable Cox regression analyses were performed to investigate S100B as a potential predictor of mortality or graft failure.
Results: Five hundred eighty-one RTRs participated in the study. The median S100B concentration was 0.19 (0.14–0.25) µg/l. Recipient age (beta=0.009, p=0.02), body mass index (BMI) (beta=0.021, p<0.001), and creatinine clearance (beta=–015, p<0.001) were independently associated with S100B. During follow-up, 95 RTRs (16.4%) died and 41 (7.1%) developed graft failure. S100B levels did not predict mortality or graft failure.
Conclusions: BMI, creatinine clearance, and age are determinants of steady-state serum S100B concentrations in renal transplant recipients. The association of BMI with S100B suggests that S100B might be a new adipokine.

Keywords: Linear Models, Kidney Transplantation, Creatinine - blood, Cell Death, Body Mass Index, Biological Markers - blood, Nerve Growth Factors - blood, S100 Calcium Binding Protein beta Subunit, S100 Proteins - blood