Human Immunodeficiency Virus Type 1- and Cytomegalovirus-Specific Cytotoxic T Lymphocytes Can Persist at High Frequency for Prolonged Periods in the Absence of Circulating Peripheral CD4+ T Cells
Spiegel HML., Ogg GS., DeFalcon E., Sheehy ME., Monard S., Haslett PAJ., Gillespie G., Donahoe SM., Pollack H., Borkowsky W., McMichael AJ., Nixon DF.
<jats:title>ABSTRACT</jats:title> <jats:p>CD4<jats:sup>+</jats:sup> T cells are thought to be critical in the maintenance of virus-specific CD8<jats:sup>+</jats:sup> cytotoxic T-cell (CTL) responses. In human immunodeficiency virus type 1 (HIV-1) infection, a selective decline in HIV-1-specific CTL as the CD4<jats:sup>+</jats:sup> T-cell count decreases has been reported. Using HLA-peptide tetrameric complexes, we show the presence at high frequency of HIV-1- and cytomegalovirus-specific CD8<jats:sup>+</jats:sup> T cells when the peripheral CD4<jats:sup>+</jats:sup> T-cell count was low or zero in three HIV-1-infected patients. No direct virus-specific CD8<jats:sup>+</jats:sup>-mediated effector activity was seen in these subjects, suggesting antigen unresponsiveness, although tetramer-sorted cells could be expanded in vitro in the presence of interleukin-2 into responsive effector cells. Thus, virus-specific CD8<jats:sup>+</jats:sup> T cells can be maintained in the peripheral circulation at high frequency in the absence of circulating peripheral CD4<jats:sup>+</jats:sup> T cells, but these cells may lack direct effector activity. Strategies designed to overcome this antigen unresponsiveness may be of value in therapies for the treatment of AIDS.</jats:p>