Neopterin and interferon-gamma in serum and cerebrospinal fluid of patients with HIV-associated neurologic disease.

We measured the levels of interferon-gamma (IFN-gamma) and neopterin in the serum and cerebrospinal fluid of 121 human immunodeficiency virus-seropositive (HIV+) and 62-seronegative (HIV-) individuals evaluated for neurologic disease. CSF levels of IFN-gamma and serum and CSF levels of neopterin were higher in HIV+ than in HIV- individuals. Patients with HIV- related meningitis and with opportunistic CNS infections had higher serum neopterin levels than HIV+ asymptomatic individuals. CSF levels of IFN-gamma were slightly higher in CSF of HIV+ individuals in all groups (0.31 +/- 0.03 U/ml) than in HIV- individuals (0.12 +/- 0.03). CSF levels of neopterin were similar in HIV+ asymptomatic individuals (6.9 +/- 0.7 nmol/l) and HIV- individuals (5.9 +/- 1.1), but were elevated in those HIV-infected individuals with neurologic disease, particularly patients with HIV-associated meningitis (72.1 +/- 13.3 nmol/l), opportunistic CNS infections (36 +/- 9.1), and inflammatory demyelinating polyneuropathies (32.4 +/- 17.2). Levels of neopterin correlated positively with levels of soluble interleukin 2 receptor and soluble CD8, 2 additional indicators of immune activation. In the absence of neurologic disease, levels of IFN-gamma and neopterin in both serum and CSF were stable for up to 4 years after seroconversion. These data suggest that increased CSF neopterin is associated with HIV-associated neurologic disease.