Prognostic value of soluble interleukin 2 receptor levels in Langerhans cell histiocytosis

We investigated the prognostic significance of soluble interleukin 2 receptor (sIL-2r) levels in the pre- and post-treatment serum of paediatric patients with Langerhans cell histiocytosis (LCH). Serum levels of sIL-2r from 32 LCH patients and 14 healthy controls were determined using enzyme-linked immunosorbent assay. The LCH patients were classified, evaluated and treated according to the Histiocyte Society's protocols. The following clinical stages were considered: single-system disease (A) divided into single-site (A1; n=4), multiple-site (A2; n=9), and multisystem disease (B) without organ dysfunction (B1; n=5) and with organ dysfunction (B2; n=14). Pretreatment concentrations of sIL-2r were markedly increased at diagnosis in LCH patients compared with controls [in pg/ml, median (range) 9200 (1124-40000) versus 610 (343-800)], P <0.0001. Levels differed significantly between stages A [3250 (1124-11000)] and B [22750 (3400-40000)], P<0.05, and between substages A2 and B2, P <0.05. There was a significant correlation between clinical stages and sIL-2r serum levels, r=0.7996 (P <0.0001). Patients with greater than or equal to17500 pg/ml of sIL-2r had a 30-month survival of 0.417 (SEM: 0.142) compared with those with levels <17500 pg/ml, who presented a 30-month survival of 0.848 (SEM: 0.100) (log-rank, P <0.0001). In multivariate analysis, sIL-2r levels greater than or equal to17500 pg/ml were found to have greater predictive strength than other well-known prognostic factors.