title: CD8+ T cells and risk for bacterial pneumonia and all-cause mortality among HIV-infected women.
abstract: BACKGROUND
  Bacterial pneumonia risk is disproportionately high among those infected with HIV. This risk is present across all CD4(+) T-cell levels (TCLs), suggesting that additional factors govern susceptibility. This study examines CD8(+) TCLs and risk for HIV-associated bacterial pneumonia and all-cause mortality.
  
  
  METHODS
  Demographic, clinical, and laboratory data were obtained for 885 HIV-infected women enrolled in the HIV Epidemiologic Research Study (HERS). Bacterial pneumonia cases were identified using clinical, microbiological, and radiographic criteria. CD8(+) TCLs were assessed at 6-month intervals. Statistical methods included Cox proportional hazards regression modeling and covariate-adjusted survival estimates.
  
  
  RESULTS
  Relative to a referent CD8(+) TCL of 401-800 cells per cubic millimeter, risk for bacterial pneumonia was significantly higher when CD8(+) TCLs were <400 (hazard ratio 1.65, P = 0.017, 95% confidence interval 1.10 to 2.49), after adjusting for age, CD4(+) TCL, viral load, and antiretroviral use. There was also a significantly higher risk of death when CD8(+) TCLs were ≤400 cells per cubic millimeter (hazard ratio 1.45, P = 0.04, 95% confidence interval 1.02 to 2.06). Covariate-adjusted survival estimates revealed shorter time to pneumonia and death in this CD8(+) TCL category, and the overall associations of the categorized CD8(+) TCL with bacterial pneumonia and all-cause mortality were each statistically significant (P = 0.017 and P < 0.0001, respectively).
  
  
  CONCLUSIONS
  CD8(+) TCL ≤400 cells per cubic millimeter was associated with increased risk for pneumonia and all-cause mortality in HIV-infected women in the HERS cohort, suggesting that CD8(+) TCL could serve as an adjunctive biomarker of pneumonia risk and mortality in HIV-infected individuals.
authors.affiliation: Department of Medicine, Division of Infectious Diseases, Albert Einstein College of Medicine, Bronx, NY 10461, USA.
authors.forename: Shruti K
authors.initials: SK
authors.lastname: Gohil
authors.forename: Moonseong
authors.initials: M
authors.lastname: Heo
authors.forename: Ellie E
authors.initials: EE
authors.lastname: Schoenbaum
authors.forename: David
authors.initials: D
authors.lastname: Celentano
authors.forename: Liise-anne
authors.initials: LA
authors.lastname: Pirofski
mesh_terms: D000293:Adolescent; D000328:Adult; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology*; D005260:Female; D015658:HIV Infections / Q000150:complications* / Q000276:immunology*; D006801:Humans; D018655:Lymphocyte Count; D008875:Middle Aged; D018410:Pneumonia, Bacterial / Q000453:epidemiology* / Q000401:mortality*; D011446:Prospective Studies; D018570:Risk Assessment; D016019:Survival Analysis; D055815:Young Adult