Cerebrospinal Fluid Interleukin-6 Is a Potential Diagnostic Biomarker for Central Nervous System Involvement in Adult Acute Myeloid Leukemia

Abstract

Objective: We evaluated the relationship between cerebrospinal fluid (CSF) cytokine levels and central nervous system (CNS) involvement in adult acute myeloid leukemia (AML). Methods: The study sample consisted of 90 patients diagnosed with AML and 20 with unrelated CNS involvement. The AML group was divided into two sub-groups: those with (CNS+, n=30) and without CNS involvement (CNS-, n=60). We used a cytometric bead assay to measure CSF interleukin (IL)-2, -4, -6, and -10, tumor necrosis factor-α, interferon-γ, and IL-17A. We used receiver operating characteristic curves to assess the ability of CSF cytokine levels to identify CNS involvement in adult AML. Results: CSF IL-6 levels were significantly higher in CNS+adult AML patients and positively correlated with the lactate dehydrogenase levels (r=0.625, p<0.001) and white blood cell (WBC) count (r=0.534, p=0.001) in the blood, as well as the protein (r=0.404, p=0.027) and WBC count in the CSF (r=0.459, p=0.011). Using a CSF IL-6 cut-off value of 8.27 pg/ml yielded a diagnostic sensitivity and specificity was 89.29% and 88.46%, respectively (AUC, 0.9184; 95% CI, 0.8568-0.9800). After treating a subset of tested patients, their CSF IL-6 concentration decreased. Consequently, the elevated CSF IL-6 levels remaining in CNS+ adult AML patients post-treatment were associated with disease progression. Conclusion: CSF IL-6 is a promising marker for the diagnosis of adult AML with CNS involvement and a crucial dynamic indicator for therapeutic response.