Immune biomarkers and secondary hemophagocytic lymphohistiocytosis: a scoping review protocol.

Objective: The objective of this review is to identify immunological pathways and markers of severity of illness associated with clinical outcomes that may represent potential therapeutic targets in the management of secondary hemophagocytic lymphohistiocytosis.

Introduction: A broad range of immunomodulatory therapies is used to manage hemophagocytic lymphohistiocytosis, however, the supporting evidence for these therapies is scarce. Identifying patients likely to experience more severe disease or die is currently extremely difficult, if not impossible. The identification of implicated cytokines in secondary disease can provide further support for the identification of high-risk patients and the development of targeted therapies.

Inclusion criteria: Studies reporting immune biomarker and cytokine measurement in adult patients (age ≥18 years) with secondary hemophagocytic lymphohistiocytosis will be considered for inclusion.

Methods: The proposed review will be conducted in line with the JBI methodology for scoping reviews. MEDLINE (Ovid) and Embase (Ovid) will be searched, without date limitations. Data will be extracted using a data extraction tool developed by the reviewers. Relevant sources will be retrieved, and their citation details imported into the JBI System for the Unified Management, Assessment and Review of Information.

Review registration: Open Science Framework https://osf.io/9524e.