Figure 4.

Siglec-1^hiCD4⁺MDM transfer human immunodeficiency virus type 1 (HIV-1) to Siglec-1^LoCD4⁻MDM. (A) M-CSF-derived monocyte-derived macrophage (MDM) from three donors were incubated with media or with HIV-1 (BaL) for 1 h at 37°C/5% CO₂. Cells were washed and fractionated into Siglec-1^hiCD4⁺MDM and Siglec-1^LoCD4⁻MDM. The infected Siglec-1^LoCD4⁻MDM were subsequently labeled with PKH-26. Both subsets were cultured at 37°C/5% CO₂. (A) Plots show the percentage of infected cells at 3 days postculture in the infected Siglec-1^hiCD4⁺MDM and (B) the infected Siglec-1^LoCD4⁻MDM. (C) HIV-1 exposed Siglec-1^hiCD4⁺MDM were cocultured with PKH-67-labeled uninfected Siglec-1^LoCD4⁻MDM. Plots show evidence of HIV-1 infection in both the Siglec-1^hiCD4⁺MDM and the PKH-67-labeled Siglec-1^LoCD4⁻MDM. (D) In parallel, PKH-26-labeled HIV-1-exposed Siglec-1^LoCD4⁻MDM were cocultured with uninfected Siglec-1^hiCD4⁺MDM. Plots show evidence of HIV-1 infection mostly in the PKH-26-labeled Siglec-1^LoCD4⁻MDM.