Intrathecal immune activation is associated with cerebrospinal fluid markers of neuronal destruction in AIDS patients.

We analysed the relationship between cerebrospinal fluid (CSF) concentrations of the light subunit of the neurofilament protein (NFL, a marker of neurons, mainly axons), neopterin (a marker of immune activation), and quantitative HIV RNA levels in 47 patients with HIV-1 infection, 25 of whom had AIDS. In the AIDS patients, the mean levels of CSF NFL were high indicating neuronal destruction. The CSF NFL and the CSF neopterin concentrations were correlated in the subgroup of patients without CNS opportunistic infection (p < 0.05). There was no significant correlation between NFL and HIV RNA levels in CSF. In HIV seropositive patients without AIDS, only 3/22 had CSF NFL concentrations above the upper normal reference value. The results suggest that CNS neuronal destruction occurs frequently in patients with AIDS but rarely in those without AIDS, and that immune activation rather than the HIV viral load is associated with neurochemical signs of axonal destruction.