sCD25 as an independent adverse prognostic factor in adult HLH patients: results of a multicenter retrospective study.

Hemophagocytic lymphohistiocytosis (HLH) is a rare but often fatal hyperinflammatory syndrome caused by an inborn or acquired error of immunity. In adults, the underlying immunodeficiency generally arises alongside severe infections, malignancies, autoimmune diseases, and immunosuppressive treatment. In order to analyze risk factors and outcome in adults, we conducted a multicenter retrospective study. Sixty-two adult (≥ 18 years) patients met at least one of the following inclusion criteria: (1) ≥ 5/8 HLH-2004 criteria, (2) HScore ≥ 200 plus 4 HLH-2004 criteria or (3) mutation compatible with an HLH diagnosis. The majority of patients (65%) were male and the median age at diagnosis was 53.5 years (range, 19-81 years). All patients were assigned to four etiologic subgroups based on their most likely HLH trigger. The survival probability of the four etiologic subgroups differed significantly (p = 0.004, log-rank test) with patients with an underlying malignancy having the worst clinical outcome (one-year survival probability of 21%). The parameters older age, malignant trigger, elevated serum levels of AST, creatinine, INR, LDH, sCD25 as well as a low albumin level and platelet count at treatment initiation were significantly (p < 0.1) associated with worse overall survival in the univariate Cox regression model. In multivariate analysis sCD25 remained the only significant prognostic factor (p = 0.005). Our results suggest that sCD25 could be a useful marker for the prognosis of patients with HLH that might help to stratify therapeutic interventions.