M2- or naïve-mediated suppression of M1 HIV replication is
independent of CCR5 ligands. Cells were sorted, infected, and
stimulated as described in Figs. 1 and 2. (Top) Infected
M1 cells were cocultured with either infected (filled symbols) or
uninfected (empty symbols) M1, M2, or naïve cells as described
in Fig. 3. MIP-1α, MIP-1β, and RANTES levels were measured 6 days
after infection and stimulation. (Middle and Bottom)
Infected M1 cells were cocultured with uninfected M2 or naïve
cells, in the absence or presence of a mixture of neutralizing levels
of anti-CCR5 ligand Abs (anti-MIP-1α, anti-MIP-1β, anti-RANTES; 50
μg/ml). RT activity was measured in culture supernatants 6
days after infection and stimulation in two independent experiments;
data are the average of duplicate cultures for each.
(Left) The absolute RT activity. (Right)
Relative activity normalized to the amount observed in the comparable
M1 culture. Although CCR5 ligands inhibit HIV replication by ≈50%,
their action does not account for the total inhibition of viral
replication observed in CD4 T cells nor by the activity expressed by
naïve cells.