Immunoglobulins and complement components in 37 patients infected by HIV-1 virus: Comparison of general (systemic) and intrathecal immunity

Abstract

Intrathecal (IT) immunity was assessed by simultaneous analysis of paired cerebrospinal fluid (CSF) and sera of 37 patients infected by human immunodeficiency virus-1 (HIV-1). Only 8 of these 37 patients had no neurological or neuropsychiatric symptoms. There were 3 prominent abnormalities observed: (1) IT IgA production occurred in 15 patients, IT IgM production in 14 patients, and IT IgG production in 34 patients. (2) IT Anti-HIV-1 antibody specific activity (ASA) was higher than in serum in 33 of the 37 patients indicating that IT synthesis of antibody specific for HIV-1 occurs even in asymptomatic patients; IT anti-HIV-1 antibody synthesis was not correlated with clinical severity or neurological involvement. IT anti-herpes simplex ASA was also higher than serum ASA in 6 patients indicating a possible associated herpes simplex virus infection. (3) IT production of the complement component C4 was found frequently and was highly correlated with increased serum C4. IT C3 levels were decreased in 21 of 37 patients indicating that complement activation is a frequent accompaniment of the IT immune response in HIV-1-positive patients. These results indicate a unique and localized IT immune response which is different from the pattern observed in the systemic immune compartment in HIV-1-seropositive individuals and from the pattern common to the other CNS infectious diseases.