Nadir CD4+ T-cell count and numbers of CD28+ CD4+ T-cells predict functional responses to immunizations in chronic HIV-1 infection

AIDS. 2003 Sep 26;17(14):2015-23. doi: 10.1097/00002030-200309260-00002.


Objective: To ascertain whether delaying the initiation of highly active antiretroviral therapy (HAART) compromises functional immune reconstitution in HIV-1 infection in persons who regain 'normal' CD4 T-cell counts after suppressive antiretroviral therapies.

Design: Prospective open-label study carried out at two University-affiliated HIV-outpatient clinics in the USA.

Subjects and methods: Response to immunization was used as a model for in vivo functional immune competence in 29 HIV-1 infected patients with CD4 T-cell counts > 450 x 106 cells/l and HIV-RNA < 400 copies/ml for > 12 months after HAART and nine HIV-1 seronegative controls. After immunization with tetanus toxoid, diphtheria-toxoid, and keyhole limpet hemocyanin, immune response scores (IRS) were calculated using postimmunization antibody concentrations, lymphocyte proliferation, and delayed-type hypersensitivity responses to vaccine antigens.

Results: Despite normal numbers of circulating CD4 T-cells, the CD4 T-cell nadir before HAART initiation predicted the immune response to immunization (rho = 0.5; P < 0.005) while current CD4 T-cell count did not. Likewise, CD4 T-lymphocyte expression of the co-stimulatory molecule CD28 was also an independent predictor of response to immunization (rho = 0.5; P < 0.005).

Conclusions: Even among persons who controlled HIV replication and normalized CD4 T-cell counts with HAART, pretreatment CD4 T-cell count and numbers of circulating CD4+CD28+ T-cells at immunization, but not current CD4 T-cell count, predict the ability to respond to vaccination. Delaying the initiation of HAART in chronic HIV-1 infection results in impaired functional immune restoration despite normalization of circulating CD4 T-cell numbers.

Publication types

  • Multicenter Study
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Adult
  • Aged
  • Antibody Formation / immunology
  • Antiretroviral Therapy, Highly Active / methods*
  • CD28 Antigens / immunology*
  • CD4-Positive T-Lymphocytes / immunology
  • Chronic Disease
  • Female
  • HIV Antibodies / analysis
  • HIV Infections / immunology*
  • HIV-1 / immunology*
  • Humans
  • Immunization / methods*
  • Lymphocyte Count / methods
  • Lymphocyte Subsets
  • Male
  • Middle Aged
  • Phenotype
  • Prospective Studies
  • T-Lymphocytes / immunology*


  • CD28 Antigens
  • HIV Antibodies