Two patients (3.4%) were identified as having viral meningoencephalitis: one was confirmed to have Epstein-Barr virus (EBV) meningoencephalitis with the evidence of high copies of EBV DNA in the CSF; the other was found to have high titers of anti-herpes simplex virus-IgM in the CSF. Here, CD40LG is linked to meningoencephalitis.