title: Effects of human immunodeficiency virus encephalitis and drug abuse on the B lymphocyte population of the brain.
abstract: We aimed to assess the effects of human immunodeficiency virus (HIV) encephalitis (HIVE) on the B-lymphocyte population of the brain. We also tested the effects of intravenous opiate drug abuse because this is a major risk factor for infection, with known immunosuppressive properties. Immunohistochemistry was used to identify B lymphocytes in the brains of clinically well-characterized HIV-negative drug abusers, individuals with HIVE, and, for comparison, HIV-negative individuals with encephalitis. Perivascular and parenchymal B lymphocytes were studied in 11 regions of each brain. We found that despite a small apparent rise, the abuse of opiate drugs had no significant effect on the B-lymphocyte population of the brain. Individuals with HIVE were found to have a greater number of B lymphocytes in brain tissue than individuals with acquired immunodeficiency syndrome (AIDS) who had no central nervous system (CNS) pathology. However, in comparison to nonimmunocompromised individuals with encephalitis, the B-lymphocyte population of HIVE brains was greatly reduced. We suggest that this latter finding may be linked to declining CD4 T-lymphocyte levels in end-stage AIDS, and that CD4 T lymphocytes may be required for efficient entry of B lymphocytes to the CNS. The brain B-lymphocyte population correlated well with CD4 T-lymphocyte level in the blood, in cases with viral encephalitis. These findings suggest that systemic immune competence is required to mount a full B-lymphocyte response to viral CNS infections. Furthermore, we suggest that CD4 T lymphocytes may play a key role in the humoral immune response to viral infection of the brain.
authors.affiliation: Neuropathology Unit, University of Edinburgh, Western General Hospital, Edinburgh, United Kingdom.
authors.forename: Iain C
authors.initials: IC
authors.lastname: Anthony
authors.forename: Dorothy H
authors.initials: DH
authors.lastname: Crawford
authors.forename: Jeanne E
authors.initials: JE
authors.lastname: Bell
mesh_terms: D015526:AIDS Dementia Complex / Q000209:etiology / Q000276:immunology*; D000163:Acquired Immunodeficiency Syndrome / Q000150:complications / Q000276:immunology; D000328:Adult; D000368:Aged; D000818:Animals; D001402:B-Lymphocytes / Q000276:immunology*; D001921:Brain / Q000276:immunology*; D015496:CD4-Positive T-Lymphocytes / Q000166:cytology / Q000276:immunology; D004660:Encephalitis / Q000276:immunology; D005260:Female; D006678:HIV / Q000276:immunology; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D008875:Middle Aged; D009294:Narcotics; D012307:Risk Factors; D015819:Substance Abuse, Intravenous / Q000276:immunology*
chemical_list: D009294:Narcotics