HCMV infection does not induce maturation of DCs and modifies the expression of cell-surface molecules on immature DCs.

The effect of HCMV infection on the expression of MHC class I, MHC class II, costimulatory molecules, and CD83 was investigated by FACS analysis on immature DCs. DCs were generated in the presence of GM-CSF and IL-4. On day 5 of the culture they were either mock infected or were infected with HCMV_TB40/E (MOI = 10). Immunofluorescent labeling of cell-surface molecules and intracellular staining of fixed and permeabilized cells with FITC-conjugated HCMV pp52 antigen were carried out 2 days after infection as described in “Patients, materials, and methods.” (A) A representative experiment showing the original FACS data of the expression of cell-surface molecules on mock-infected (first row) or HCMV-infected (second row) immature DCs. The Y axes represent the mean fluorescence intensity (MFI) of surface molecules indicated above the dot plots and on the X axes the MFI of the HCMV pp52-specific antibody is shown. Throughout this paper, DCs from HCMV-infected cultures were described either as HCMV Ag negative (left side of dot plots in the second row) or HCMV Ag positive (right side of dot plots in the second row) representing uninfected and infected DCs, respectively. (B) The relative fluorescence intensity (RFI) of surface molecules on Ag-positive DCs are shown. Means and standard deviations were calculated from 3 to 4 experiments. Each data point represented the RFI of a given surface molecule (M) on HCMV Ag-positive DCs, calculated as: (MFI ofM on HCMV Ag-positive DCs / MFI of M on mock-infected DCs) × 100.