Abstract
The chemokine receptor CCR5 is expressed on multiple cell types, including macrophages, dendritic cells, and T cells, and is the major co-receptor used during HIV transmission. Using a standard αCD3/CD28 in vitro stimulation protocol to render CD4+ T cells from PBMCs permissive to HIV infection, we discovered that the percentage of CCR5+ T cells was significantly elevated in CD4+ T cells when stimulated in the presence of peripheral blood mononuclear cells (PBMCs) as compared to when stimulated as purified CD4+ T cells. This indicated that environmental factors unique to the T-PBMCs condition affect surface expression of CCR5 on CD4+ T cells. Conditioned media from αCD3/CD28-stimulated PBMCs induced CCR5 expression in cultures of unstimulated cells. Cytokine profile analysis of these media suggests IL-12 as an inducer of CCR5 expression. Mass cytometric analysis showed that stimulated T-PBMCs exhibited a uniquely activated phenotype compared to T-Pure. In line with increased CCR5 expression and activation status in stimulated T-PBMCs, CD4+ T cells from these cultures were more susceptible to infection by CCR5-tropic HIV-1 as compared with T-Pure cells. These results suggest that in order to increase ex vivo infection rates of blood-derived CD4+ T cells, standard stimulation protocols used in HIV infection studies should implement T-PBMCs or purified CD4+ T cells should be supplemented with IL-12.
Highlights
Immune cells, including CD4+ T cells, express a diverse array of chemokine receptors in a regulated fashion, and the expression patterns of these receptors dictate trafficking between lymphoid tissues and the periphery
In this study we investigated how the environmental context of culturing CD4+ T cells affects the expression of chemokine receptor type 5 (CCR5) and susceptibility to infection by human immunodeficiency virus type 1 (HIV-1)
We demonstrate that CCR5 expression on CD4+ T cells is greatly dependent on the context in which the CD4+ T cells are stimulated
Summary
Immune cells, including CD4+ T cells, express a diverse array of chemokine receptors in a regulated fashion, and the expression patterns of these receptors dictate trafficking between lymphoid tissues and the periphery. Long term stimulation with Interleukin (IL)-2 increases CCR5 expression (Bleul et al, 1997; Wang et al, 1999; Yang et al, 2001) and IL-12 upregulates CCR5 expression on TCR-stimulated human and murine CD4+ T cells (Iwasaki et al, 2001; Mukai et al, 2001; Yang et al, 2001) Other cytokines such as tumor necrosis factor alpha (TNFα) and interferon-gamma (IFN-γ) have been found to promote upregulation of CCR5 on CD4+ T cells and monocytes, whereas IL-10 has been found to downregulate CCR5 expression (Hariharan et al, 1999; Patterson et al, 1999)
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