Intrathecal synthesis of beta 2-microglobulin and lysozyme: differential markers of nervous system involvement in patients infected with human immunodeficiency virus type 1.

beta 2-Microglobulin and lysozyme were determined in paired serum and cerebrospinal fluid samples from 137 patients, using immunofluorometry and ELISA, respectively. Of these patients, 54 were infected by human immunodeficiency virus type 1 (HIV1) (including 20 AIDS dementia patients), 73 were HIV1-seronegative with neurological diseases (meningitis (n = 10), multiple sclerosis (n = 29), other neurological diseases (n = 34)) and 10 were controls. Intrathecal synthesis of beta 2-microglobulin occurred in each group. Conversely, lysozyme intrathecal synthesis was found only in meningitis (10/10) and in HIV1-infection (24/54). A pathological increase in beta 2-microglobulin intrathecal synthesis (> or = 2 mg/l) was observed in 45 patients (34 HIV1-infected patients and 11 HIV1-seronegative patients with neurological diseases). Serum concentration and intrathecal synthesis of beta 2-microglobulin were correlated only in the 20 AIDS dementia patients. The cerebrospinal fluid beta 2-microglobulin and lysozyme concentrations were correlated in the 54 HIV1-infected patients only. Blood CD4 + T-cell count was correlated negatively with beta 2-microglobulin intrathecal synthesis but not with lysozyme intrathecal synthesis. These data suggest that in the absence of any central nervous system opportunistic process the increase of beta 2-microglobulin intrathecal synthesis (> or = 2 mg/l) may be a reliable marker of central nervous system involvement in HIV1-infected patients. Intrathecal synthesis of lysozyme was related principally to HIV1-encephalitis and central nervous system opportunistic processes.