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Phenotypically defined memory CD4+ cells are not selectively decreased in chronic HIV disease
C C Chou1, V Gudeman, S O'Rourke
1Department of Medicine, UCLA School of Medicine 90024-1745.
Journal of Acquired Immune Deficiency Syndromes
|July 1, 1994
Summary
HIV infection partly reduces memory CD4+ cell function, but not their proportion. AIDS patients paradoxically show increased memory CD4+ cells, unaffected by zidovudine treatment.
Area of Science:
- Immunology
- Virology
- Cell Biology
Background:
- Human Immunodeficiency Virus (HIV) infection is known to impair immune responses.
- Memory CD4+ T cells are crucial for adaptive immunity and recall responses.
- Previous studies suggested a decline in memory CD4+ cells in HIV-infected individuals.
Purpose of the Study:
- To simultaneously assess memory CD4+ T cell numbers and their proliferative function in response to recall antigens in HIV-infected subjects.
- To determine if reduced immune responses in HIV infection are solely due to decreased memory CD4+ T cell numbers.
- To investigate the effect of zidovudine (ZDV) on immune responses in HIV-infected patients.
Main Methods:
- Simultaneous measurement of phenotypically defined memory CD4+ T cells and in vitro proliferation assays to tetanus toxoid, influenza, and Candida albicans.
- Comparison between 53 HIV-seropositive subjects and 39 HIV-seronegative controls.
- Analysis of zidovudine (ZDV), dideoxycytidine (ddC), and azido-dideoxyuridine (AZU) effects on proliferative responses.
Main Results:
- Low proliferative responses to recall antigens in HIV-infected individuals were only partly explained by decreased memory CD4+ T cell numbers.
- The proportion of memory CD4+ T cells was not selectively decreased in HIV-seropositive subjects compared to controls.
- AIDS patients exhibited a significant increase in the proportion of memory CD4+ T cells, especially with very low CD4+ counts.
- Zidovudine (ZDV) treatment showed no evidence of enhancing in vivo or in vitro proliferative responses to recall antigens.
Conclusions:
- Reduced immune function in HIV infection is not solely attributable to a loss of memory CD4+ T cells.
- The increase in memory CD4+ T cell proportion in AIDS patients suggests a complex dysregulation of T cell populations.
- Current antiretroviral therapies like ZDV do not appear to restore proliferative responses to recall antigens.