Langerhans cell histiocytosis in children: does soluble interleukin-2-receptor correlate with both disease extent and activity?

Abstract

Langerhans cell histiocytosis (LCH) is characterized by monoclonal proliferation of activated Langerhans cells. Neither etiology nor pathomechanism of this disorder is presently known. However, despite monoclonality LCH might represent a reactive clonal disorder induced by immune dysfunction rather than a malignant process. To investigate a putative cytokine dysregulation in the pathogenesis of this disorder and searching for parameters of both disease activity and prognosis, serum concentrations of proinflammatory and T-cell derived cytokines were evaluated in LCH patients. Serum levels of IL-1 beta, IL-2, sIL-2R and TNF-alpha were determined by ELISA in seven children with different types of LCH: Three children (aged 6, 10 and 14 years, respectively) with single system/single bone disease; one child (11 years) with recurrent single system/multiple bone disease and three children (1, 2 and 2 years, respectively) with multisystem disease. sIL-2R was elevated at diagnosis in seven children as compared to healthy adults (mean +/- SEM: 5,256 +/- 3,751 U/ml vs. 73 +/- 5.5 U/ml; P < 0.005) or healthy children (mean +/- SEM: 10,195 +/- 2,798 pg/ml vs. 2,638 +/- 156 pg/ml; P < 0.01). A positive correlation between serum levels of sIL-2R and extent of the disease could be observed. During remission, sIL-2R levels declined. IL-1 beta, IL-2, and TNF-alpha remained within the normal range during the study period. Elevated sIL-2R levels seem to correlate positively with both extent and activity of LCH, thus indicating a pathological T-cell activation as a pathogenetic factor. sIL-2R level is a promising parameter to monitor disease activity in LCH and may also be of prognostic relevance.