B-cell-activating factor belonging to the tumor necrosis factor family (BAFF) and a proliferation-inducing ligand (APRIL) levels in cerebrospinal fluid of patients with meningoencephalitis.

The B-cell-activating factor belonging to the tumor necrosis factor family (BAFF) and a proliferation-inducing ligand (APRIL) are important factors for the survival of transitional and mature B cells. High levels of BAFF and APRIL are present in adults with several autoimmune diseases. However, there are few reports about BAFF and APRIL levels in the cerebrospinal fluid (CSF) of patients with meningoencephalitis. We evaluated BAFF and APRIL levels in CSF samples from patients with viral meningitis (VM) (28 patients), autoimmune encephalitis (AE) associated with antineuronal antibodies (15 patients), idiopathic normal pressure hydrocephalus (iNPH) (11 patients), herpes simplex encephalitis (HSE) (9 patients), bacterial meningitis (BM) (6 patients), and cryptococcal meningitis (CM) (4 patients). The CSF BAFF levels were significantly higher in patients with HSE, BM, or VM than AE or iNPH, and significantly higher in patients with CM than iNPH. The CSF APRIL levels were significantly higher in patients with HSE or BM than AE, VM, or iNPH. Although this is a preliminary report due to within-group variation and small sample size, the data suggest that CSF BAFF and APRIL levels are increased in HSE and BM, but not AE.