title: Dysregulation of CD28 and CTLA-4 expression by CD4 T cells from previously immunodeficient HIV-infected patients with sustained virological responses to highly active antiretroviral therapy.
abstract: OBJECTIVE
  Current guidelines recommend commencing highly active antiretroviral therapy (HAART) in HIV-infected patients when CD4 T-cell counts reach 350 cells/microL. However, late-presenting HIV-infected patients with CD4 T-cell counts<50 cells/microL are still common. The ability of long-term HAART to normalize immune dysregulation in severely immunodeficient HIV-infected patients remains unclear. Here we address indices of immune dysregulation in previously severely immunocompromised HIV-infected patients treated with long-term HAART who had achieved increased CD4 T-cell counts and complete suppression of HIV viraemia.
  
  
  METHODS
  We examined expression of CD28, cytotoxic T-lymphocyte antigen-4 (CTLA-4) and intracellular perforin by CD4 and CD8 lymphocytes from 25 highly selected HIV-infected patients [nadir CD4 T-cell counts <50 cells/microL, >4 years on HAART and >6 months of complete viral suppression (<50 HIV-1 RNA copies/mL)] and 18 HIV-seronegative age- and sex-matched controls.
  
  
  RESULTS
  HIV-infected patients had lower percentages of CD28-expressing CD4 lymphocytes and higher percentages of CTLA-4-expressing CD4 lymphocytes than controls. The percentage of CTLA-4-expressing CD4 lymphocytes correlated inversely with that of CD28-expressing CD4 lymphocytes. The proportion of CD4 lymphocytes expressing perforin was generally low. However, more HIV-infected patients than controls had >1% of CD4 lymphocytes expressing perforin [11 of 25 (44%) vs. one of 18 (5.5%)]. The percentage of CD8 lymphocytes expressing perforin did not differ between HIV-infected patients and controls. Amongst HIV-infected patients, the percentage of perforin-expressing CD8 lymphocytes correlated inversely with nadir but not current CD4 T-cell count.
  
  
  CONCLUSIONS
  Expression of CD28, CTLA-4 and perforin by CD4 lymphocytes remain dysregulated in HIV-infected patients with previous severe immunodeficiency, despite increased CD4 T-cell counts and control of HIV viraemia by HAART.
authors: Department of Clinical Immunology and Biochemical Genetics, Royal Perth Hospital and School of Surgery and Pathology, University of Western Australia, Perth, Australia. sfstone@graduate.uwa.edu.au
authors: S F
authors: SF
authors: Stone
authors: P
authors: P
authors: Price
authors: M A
authors: MA
authors: French
mesh_terms: D015703:Antigens, CD; D000943:Antigens, Differentiation / Q000032:analysis / Q000276:immunology*; D023241:Antiretroviral Therapy, Highly Active / Q000379:methods*; D018106:CD28 Antigens / Q000032:analysis / Q000276:immunology*; D018791:CD4 Lymphocyte Count / Q000379:methods; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology*; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology; D060908:CTLA-4 Antigen; D015658:HIV Infections / Q000188:drug therapy* / Q000276:immunology / Q000821:virology; D006801:Humans; D007166:Immunosuppressive Agents / Q000032:analysis / Q000276:immunology; D008562:Membrane Glycoproteins / Q000276:immunology; D054353:Perforin; D010641:Phenotype; D052899:Pore Forming Cytotoxic Proteins; D019562:Viral Load
chemical_list: D015703:Antigens, CD; D000943:Antigens, Differentiation; D018106:CD28 Antigens; D060908:CTLA-4 Antigen; C556706:CTLA4 protein, human; D007166:Immunosuppressive Agents; D008562:Membrane Glycoproteins; D052899:Pore Forming Cytotoxic Proteins; D054353:Perforin