Neopterin and β2-microglobulin and the assessment of intra-blood-brain-barrier synthesis of hiv-specific and total igg

In HIV‐seropositive patients, we evaluated the clinical utility of measuring combinations of serum and CSF levels of neopterin and β2‐microglobulin (β2‐M) (by RIA), as well as the intra‐blood‐brain‐barrier (IBBB) IgG Synthesis rate, IgG index, and HIV antibody index (by rate nephelometry, EIA, and formulae) for the assessment of HIV infection of the CNS. We studied paired sera and CSF from 31 HIV‐seropositive patients: asymptomatic (16), ARC (12), and AIDS (3). A normal serum neopterin level predicts normal levels of serum β2‐M, CSF neopterin, or CSF β2‐M in 90%, 100%, and 100%, respectively, of our patients. An elevated serum neopterin level predicts an elevated level of serum β2‐M or CSF neopterin in 81% and 62%, respectively, of cases. The HIV antibody index and IBBB IgG synthesis rate or IgG index must be determined separately because they do not predict each other and are not predicted by levels of neopterin or β2‐M.