Interleukin-2 serum levels are elevated in patients with uremic pruritus: a novel finding with practical implications

Background. Uremic pruritus (UP) is still a common tormenting symptom among patients on hemodialysis (HD). The pathogenesis of UP is complex and not fully clarified. Some preliminary studies indicate that UP is a systemic inflammatory disease with a deranged balance of T helper (TH) cell differentiation toward TH1 predominance. The aim of this study was to further elucidate the potential contribution of TH1 cytokines to the pathogenesis of UP. Methods. In this study, 112 HD patients were screened for UP. After meeting the required criteria, 31 HD patients with UP were included in the study as case group and 30 age-and sex-matched HD patients without UP were enrolled as controls. The serum levels of interleukin (IL)-2 and interferon-gamma (as TH1 cytokines), IL-4 (as a TH-2 cytokine), high-sensitive C-reactive protein (as an inflammatory marker), parathyroid hormone, calcium, phosphate, albumin and ferritin were measured in all patients. Moreover, blood variables including hemoglobin and mean corpuscular volume were also determined. The correlations of measured factors with UP severity were determined as well. Results. Except for the serum levels of IL-2, which were significantly higher in HD patients with itch versus those without it [0.544 +/- 0.126 (U/mL) versus 0.318 +/- 0.145 (U/mL); P < 0.0001], no statistically significant difference was observed in the levels of each of the above-mentioned factors between the two groups. Additionally, no correlation was detected between the levels of measured factors and UP severity. Conclusions. The results of our study, for the first time, point to the potential important role of IL-2 in UP and further support the notion of TH1 overactivity in its pathogenesis. Our study paves the way for further studies focusing on the contribution of IL-2 to the UP, such as the experimental use of anti-IL-2 receptor antibodies.