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Activation of CD8+ T lymphocytes through the T cell receptor turns on CD4 gene expression: implications for HIV
L Flamand1, R W Crowley, P Lusso
1Institute of Human Virology, University of Maryland Biotechnology Institute at Baltimore, 725 West Lombard Street, Baltimore, MD 21201-1192, USA.
Abstract:
T cell activation through the T cell receptor is necessary to achieve a specific and effective immune response. We report here that stimulation of CD8+ T cells through the T cell receptor complex leads to de novo expression of the CD4 antigen on the cell surface that results in susceptibility of CD8+ T cells to HIV infection. In addition, activation of peripheral blood mononuclear cells from HIV-infected individuals results in the appearance of double-positive CD4+/CD8+ T cells, which become infected by endogenous HIV. HIV DNA sequences could be detected in uncultured and sorted mature CD3+CD8+ T cells from HIV+ individuals. These results suggest a new mechanism by which HIV could attack the immune system and may help to explain the CD8+ T cell defects in AIDS patients.