A spectrum of neurological diseases with elevated cerebrospinal fluid adenosine deaminase levels

This study aimed to investigate cerebrospinal fluid (CSF) adenosine deaminase (ADA) levels in various neurological disorders and examine the relationships between CSF ADA levels and immunological parameters.

Overall, 276 patients whose CSF ADA levels were measured for suspected tuberculous meningitis (TBM) were evaluated. Data on baseline characteristics, final diagnoses, CSF ADA levels, and other laboratory parameters were collected. Thereafter, CSF ADA levels were compared based on final diagnoses, and correlations between CSF ADA levels and other CSF and blood laboratory parameters were evaluated.

Five diseases exhibited a significant increase in CSF ADA levels relative to the noninflammatory disease control group (n = 40): (1) TBM (n = 15, p < 0.0001), (2) fungal meningitis (n = 7, p = 0.0400), (3) autoimmune glial fibrillary acidic protein astrocytopathy (GFAP-A, n = 7, p < 0.0001), (4) neurosarcoidosis (n = 7, p = 0.0028), and (5) lymphoproliferative disorders (n = 18, p = 0.0001). Strong positive correlations were observed between CSF ADA and CSF parameters, including soluble IL2 receptor (r_s = 0.7566, p < 0.0001), albumin (r_s = 0.6693, p < 0.0001), lactate dehydrogenase (r_s = 0.6452, p < 0.0001), white blood cell count (r_s = 0.6035, p < 0.0001), protein (r_s = 0.6334, p < 0.0001), and lymphocytes (r_s = 0.5954, p < 0.0001).

CSF ADA levels were elevated in various inflammatory neurological diseases, especially in TBM, fungal meningitis, GFAP-A, neurosarcoidosis, and lymphoproliferative disorders. CSF ADA levels may reflect T-cell hyperactivation in the central nervous system.