Urine macrophage migration inhibitory factor concentrations as a diagnostic tool in human renal allograft rejection

Background. Macrophage migration inhibitory factor (MIF) is a pro-inflammat ory cytokine that is a potent activator of macrophages and T cells. Previou s studies have shown that local MIF production is increased in acute renal allograft rejection, suggesting that it may play an important role in the r ejection process, Aims. To determine if urine and serum MIF concentrations: (1) are increased in acute rejection, and (2) can be used as noninvasive tools to discrimina te between acute rejection (AR) and cyclosporine nephrotoxicity (CyA toxici ty). Methods. In a prospective study of nine renal allograft patients (five acut e rejection and four stable), serial urine MIF concentrations were measured by ELISA in the first 14 days after transplantation. In a retrospective st udy, MIF concentrations in urine and serum were measured in 24 patients who were biopsied for acute renal transplant dysfunction (11 AR, 13 CyA toxici ty). Urine and serum MIF were also measured in 23 stable renal transplant p atients and 10 normals. Results, MIF was readily detected in the urine of normal healthy controls ( 106+/-61 pg/mu mol creatinine), In the prospective study, the urinary MIF c oncentration was increased substantially on day 1 posttransplantation and s ubsequently fell in parallel with the serum creatinine, However, urine MIF increased before episodes of biopsy proven acute rejection. The retrospecti ve study showed that urine MIF concentrations in patients with AR were incr eased 5-fold compared to normal controls (439+/-313 pg/mu mol Cr; P<0.01). In contrast, urine MIF concentrations in CyA toxicity were not significantl y different to normal controls (145+/-119 pg/<mu>mol Cr; P=NS), A marked in crease in MIF immunostaining was seen in biopsies of AR, but not in CyA tox icity. No significant differences were evident in serum MIF levels between normals and any transplant patient group. Conclusions. These results suggest that measurement of urine MIF concentrat ion may be useful in monitoring renal transplant patients for acute rejecti on and as a discriminator from cyclosporine nephrotoxicity.