Efficient human cytomegalovirus reactivation is maturation dependent in the Langerhans dendritic cell lineage and can be studied using a CD14+ experimental latency model.
Studies from a number of laboratories have shown that the myeloid lineage is prominent in human cytomegalovirus (HCMV) latency, reactivation, dissemination, and pathogenesis. Existing as a latent infection in CD34(+) progenitors and circulating CD14(+) monocytes, reactivation is observed upon differentiation to mature macrophage or dendritic cell (DC) phenotypes. Langerhans' cells (LCs) are a subset of periphery resident DCs that represent a DC population likely to encounter HCMV early during primary infection. Furthermore, we have previously shown that CD34(+) derived LCs are a site of HCMV reactivation ex vivo. Accordingly, we have utilized healthy-donor CD34(+) cells to study latency and reactivation of HCMV in LCs. However, the increasing difficulty acquiring healthy-donor CD34(+) cells--particularly from seropositive donors due to the screening regimens used--led us to investigate the use of CD14(+) monocytes to generate LCs. We show here that CD14(+) monocytes cultured with transforming growth factor β generate Langerin-positive DCs (MoLCs). Consistent with observations using CD34(+) derived LCs, only mature MoLCs were permissive for HCMV infection. The lytic infection of mature MoLCs is productive and results in a marked inhibition in the capacity of these cells to promote T cell proliferation. Pertinently, differentiation of experimentally latent monocytes to the MoLC phenotype promotes reactivation in a maturation and interleukin-6 (IL-6)-dependent manner. Intriguingly, however, IL-6-mediated effects were restricted to mature LCs, in contrast to observations with classical CD14(+) derived DCs. Consequently, elucidation of the molecular basis behind the differential response of the two DC subsets should further our understanding of the fundamental mechanisms important for reactivation.
Department of Medicine, University of Cambridge, Addenbrooke's Hospital, Cambridge, United Kingdom.
Margaret M
MM
Huang
Verity G
VG
Kew
Kevin
K
Jestice
Mark R
MR
Wills
Matthew B
MB
Reeves
D018952:Antigens, CD34 / Q000032:analysis; D018929:Cell Culture Techniques / Q000379:methods; D002454:Cell Differentiation; D003587:Cytomegalovirus / Q000502:physiology*; D003713:Dendritic Cells / Q000737:chemistry / Q000276:immunology* / Q000821:virology*; D006801:Humans; D018950:Lipopolysaccharide Receptors / Q000032:analysis; D009000:Monocytes / Q000737:chemistry / Q000276:immunology / Q000821:virology; D014773:Virology / Q000379:methods; D014775:Virus Activation; D017735:Virus Latency
D018952:Antigens, CD34; D018950:Lipopolysaccharide Receptors