Clinical Significance Of Serum And Urine Soluble Interleukin 2 Receptor, C-Reactive Protein, Cystatin C, and Serum and Urine Creatinine in Renal Transplant Patients

Cytokines play a major role in the inflammatory and allo-specific components of allograft rejection, and in the migration of cells into graft tissue. IL-2 binding of sIL-2R plays a major role in T cell activation. It is suggested that high urinary sIL-2R (U/sIL-2R) in the first 3-5 post-transplant days identified the patient sub-group at risk of developing acute rejection (RX). However, it was difficult to distinguish between RX and infection (INFX) as both of these factors can potentially affect serum sIL-2R (S/sIL-2R) and U/sIL-2R concentrations independent of actual production rates. The aims of this study were to validate and extend previous findings of the use of sIL-2R in renal transplantation, to investigate other protein markers currently used such as serum C-reactive protein (CRP), serum cystatin C (cys. C), and serum and urine creatinine (S/creat. and UCRE) and attempt to differentiate RX from INFX. SIL-2R ELISA kit was validated and used to establish reference ranges in healthy donors, transplant (TX) recipients, and renal disease controls. These values were compared with serial estimations of S/sIL-2R and U/sIL-2R of patients post-TX. Levels of serum CRP, cys. C, S/creat. and UCRE were also investigated in the renal disease control and 21 TX subjects to determine if a panel of investigation would have enhanced clinical diagnosis. RX and INFX were determined retrospectively on an “intention to treat” basis. Results show that sIL-2R levels in normal serum and urine subjects are lower than in disease controls, that CRP and cys C are good indicators of RX as well as U/sIL-2R and S/sIL-2R, that UCRE is not a good marker of differentiation, and that stratifying levels of these markers according to treatment differentiated RX from INFX.