title: Existence and failure of T-cell homeostasis prior to AIDS onset in HIV-infected injection drug users.
abstract: Prior studies, based on populations of homosexual men, have shown that during HIV infection, levels of total circulating T-cells (CD3+ lymphocytes) remain constant for long periods of time after seroconversion. This suggested homeostatic phenomenon was observed to break down about 18 months prior to AIDS diagnosis with a quick loss of T-cells. The objective of this study was to determine whether (a) total T-cells are maintained at a constant level for long periods of time among HIV-infected injection drug users (IDUs) and (b) total T-cells decline before AIDS onset in this risk group and, if so, by how long. The design and setting was prospective follow-up, with semiannual clinic visits, of 646 HIV-infected IDUs who participate in the ALIVE study (Baltimore, MD). Among AIDS cases, T-cell levels remained quite stable at about 1500 cells/microl up to approximately 24 months prior to AIDS. However, a steep decline in CD3+ cell levels began approximately 24 months prior to AIDS diagnosis and was -17.5% per 6 months in the last 18 months before AIDS. Among seropositive IDUs without AIDS, a gradual decline of less than -4% per 6 months was observed. These trends remained virtually unchanged after accounting for current injection drug use, smoking, and HIV-related medications. IDUs, like homosexual men, exhibited T-cell homeostasis following HIV infection, as well as failure of this homeostasis about 2 years before AIDS. Although the mechanisms for the maintenance and later failure of the homeostasis of T-lymphocytes are not well understood, the observation has a potentially important prognostic value as well as biological interest.
authors.affiliation: Department of Epidemiology, The Johns Hopkins School of Hygiene and Public Health, Baltimore, Maryland, USA.
authors.forename: N
authors.initials: N
authors.lastname: Galai
authors.forename: J B
authors.initials: JB
authors.lastname: Margolick
authors.forename: J
authors.initials: J
authors.lastname: Astemborski
authors.forename: D
authors.initials: D
authors.lastname: Vlahov
mesh_terms: D000163:Acquired Immunodeficiency Syndrome / Q000150:complications / Q000276:immunology*; D000328:Adult; D000368:Aged; D018791:CD4 Lymphocyte Count; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology; D018450:Disease Progression; D005260:Female; D005500:Follow-Up Studies; D006706:Homeostasis / Q000276:immunology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D015819:Substance Abuse, Intravenous / Q000150:complications / Q000276:immunology*; D013601:T-Lymphocytes / Q000276:immunology*