HIV-1 replication in the plasma and cerebrospinal fluid

The HIV-1 RNA in plasma and CSF samples from 40 HIV-1 infected patients was measured by a polymerase chain reaction (PCR) technique. The possible implication of cytokines in HIV-1 replication was investigated by measuring the concentrations of tumor necrosis factor alpha (TNF-alpha), macrophage colony stimulation factor (M-CSF) and interleukin-6 (IL-6) in these fluids. HIV-1 RNA was quantified in all plasma samples and in 87.5% of the CSF samples. CSF HIV-1 RNA titers did not correlate with the stage of disease or the CD4+ T cell counts, unlike the plasma HIV-1 RNA titers. These results were confirmed when patients with a blood brain barrier damage, as assessed by the CSF/ plasma albumin ratio, were excluded from the analysis. TNF-alpha levels were statistically correlated with the HIV-1 RNA in plasma and CSF. These data demonstrate that HIV-1 replication in the CSF at each clinical stage can be accurately measured with PCR and, although the titers of HIV-1 RNA copies in the CSF are correlated with those in the plasma, the magnitude of HIV-1 replication in CSF is not directly linked to the stage of disease, or to the CD4+ T cell count. The significance of early high levels of HIV-1 RNA in CSF is now being studied prospectively.