HCMV infection of DCs inhibits LPS-induced up-regulation of cell-surface molecules.

The effect of HCMV infection on the LPS-induced expression of MHC class I, MHC class II, costimulatory molecules, and CD83 on DCs was investigated by FACS analysis. DCs were generated in the presence of GM-CSF and IL-4. On day 5 of the culture they were either mock infected or infected with HCMV_TB40/E (MOI = 10). After 48 hours, LPS was added in the presence of IFN-γ and TNF-α for 24 hours. Immunofluorescent labeling of cell-surface molecules and intracellular staining of fixed and permeabilized cells with FITC-conjugated HCMV pp52 antigen were carried out as described in “Patients, materials, and methods.” (A) A representative experiment showing original FACS data of the expression of cell-surface molecules on mock-infected (first row) or HCMV-infected (second row) DCs following LPS treatment. The Y axis represents the mean fluorescence intensity (MFI) of surface molecules as indicated above the dot plots, and the X axis indicates the binding of HCMV pp52-specific antibody. (B) The relative fluorescence intensity (RFI) of surface molecules on HCMV Ag-positive DCs following LPS treatment are shown. Means and standard deviations were calculated from 3 experiments. RFI was calculated as in Figure 1, except that the 100% expression was represented by LPS-treated mock-infected DCs.