Suppressor of cytokine signaling (SOCS) 1 is down-regulated in renal transplant recipients with rejection.

The role of suppressor of cytokine signaling (SOCS) in maintaining the immunotolerance of renal allograft is unknown. To clarify this, peripheral blood mononuclear cells (PBMCs) from renal transplant patients with or without rejection were analyzed for the expression of SOCS family proteins by cell culture, immunoblot, flowcytometry and quantitative reverse transcription-polymerase chain reaction (qPCR). Patients with renal graft rejection expressed lower levels of SOCS1 while those without rejection showed a higher SOCS1 expression in the PBMC either on stimulation or not. In addition, SOCS1 was constitutively expressed in normal individuals as well as renal transplant patients with graft tolerance while patients with rejection exhibited down-regulation of the SOCS1 but not SOCS3. The qPCR tests and flowcytometric measurements have also showed that the reduction of SOCS1 expression in rejection could be quantitatively evaluated. These results have suggested that down-regulation of SOCS1 may be regarded as a biomarker for early detection of renal allograft rejection.