IFN-α-Induced Upregulation of CCR5 Leads to Expanded HIV Tropism In Vivo
Figure 2
IFN-α induces CCR5 expression on thymocyte progenitors both in vitro and in vivo.
(A) Thymus organ cultures were incubated in triplicate with the indicated cytokines or with Tat for 3 days, and dispersed cells were stained with MAbs against CD3, CD4, CD8, and CCR5 for flow cytometry. Only treatment with IFN-α significantly increased CCR5 expression on thymocytes (left), and the ITTP subset showed the greatest increase (right). Data are representative of three independent experiments. TN are “triple-negative” CD3−CD4−CD8− thymocyte progenitors. (B) SCID-hu Thy/Liv mice from three cohorts (A, B, and C) were treated with IFN-α or sterile water (mock) by once-daily i.p. injection for 6 or 13 days, and Thy/Liv implants were collected and stained one day after the last injection or after 7 additional days of no treatment. IFN-α significantly increased the percentage of CCR5+ ITTP, which normalized within 7 days of treatment cessation. Asterisks indicate P<0.05 compared to mock-treated cultures or mice by the Mann-Whitney U test. (C) CCR5 expression on ITTP from representative mock- and IFN-α-treated (cohort C) mice. FMO is the fluorescence-minus one plot used for CCR5 gating, and percentages of CCR5+ ITTP are indicated. The mean fluorescence intensity of the CCR5+ ITTP is shown in the histogram below each dot plot.