Ratio of alpha 2-macroglobulin levels in cerebrospinal fluid and serum: an expression of neuroinflammation in acute disseminated encephalomyelitis

Abstract Background Acute encephalitis and encephalopathy (AEE) are life-threatening diseases in children. However, no laboratory examinations are performed for their early diagnosis and treatment. Alpha 2-macroglobulin (α2M) is a blood glycoprotein that increases at the early stages of inflammation. In this study, we investigated whether α2M was associated with AEE. Methods We analyzed the association between AEE and α2M using cerebrospinal fluid (CSF) and serum samples from patients with acute disseminated encephalomyelitis (ADEM), infection-related acute encephalopathy (AE), febrile status epilepticus (FSE), and febrile seizure (FS). Samples were collected in the pediatric department of hospitals throughout Fukushima Prefecture between January 1, 1999, and May 31, 2012. Results α2M levels in the CSF were quantified at 4.7 (3.8–8.4) μg/mL for ADEM, 2.1 (1.1–2.3) μg/mL for AE, 1.1 (0.9–6.4) μg/mL for FSE, and 1.0 (0.8–1.1) μg/mL for FS. α2M levels in patients with ADEM were significantly higher than those in patients with AE and FS (p = 0.019 and p = 0.002, respectively). The ratio of the α2M level in the CSF to that in the serum in patients with ADEM was significantly higher than that in patients with FSE (p = 0.04). In patients with ADEM, α2M levels in the CSF decreased with treatment. Conclusions Our results suggest that the ratio of the α2M level in the CSF to that in the serum reflects the neuroinflammatory status of patients with ADEM and indicates the expression of early neuroinflammation in ADEM.