INTRATHECAL SYNTHESIS OF IGG IN SIMIAN IMMUNODEFICIENCY VIRUS (SIV)-INFECTED RHESUS MACAQUES (MACACA-MULATTA)

We examined cerebrospinal fluid (CSF) and serum from 25 simian immunod eficiency (SIV)-infected rhesus macaques for the presence of SIV-speci fic immunoglobulin G (IgG) and for intrathecal synthesis of IgG. SIV-s pecific IgG was present in CSF from almost 50% of the macaques. In app roximately half of these animals the SIV-specific IgG appeared to be d erived from serum by leakage across a disrupted blood-brain barrier, w hereas in the remaining animals there was evidence of intrathecal IgG synthesis. There were no significant associations between CSF SIV-spec ific IgG, intrathecal IgG synthesis and isolation of virus from CSF, c linical status, or neuropathological findings. However, SIV-specific I gG was absent from CSF in all four of the macaques with SIV encephalit is. The presence of SIV-specific IgG in CSF may have a modulating effe ct on the development of SIV-associated neurological disease.