The most widely accepted theory for the massive
depletion of CD4+ T cells in HIV-1 infection
involves depletion of non-infected cells through
immune activation. A specialized cell population,
the T regulatory cells (Tregs), exists to help limit
chronic inflammation by suppressing the immune
activation induced by infectious diseases. We used
an SIV/pigtailed macaque model of HIV-1 disease to
elucidate the role of Tregs in HIV-1-induced
depletion of CD4+ T cells in lymphoid tissue during
the acute phase of infection. From this model, we
learned that Tregs play a significant role in
controlling the apoptotic loss of CD4+ T cells
resulting from high levels of generalized immune
activation. Using assays developed in the macaque
model, we next studied the role of Tregs in elite
suppressors who are HIV-1-infected individuals that
maintain normal CD4+ T cell counts and control
viremia without therapy. The assays developed
in our laboratory should be especially useful to
the future studies of both virologists and
immunologists.