LPS-matured DCs are relatively resistant to infection.

The effect of LPS-induced DC maturation on the infection rate of DCs by HCMV was studied by FACS analysis. DCs were generated in the presence of GM-CSF and IL-4. On day 5 of the culture the cells were either left untreated (A) or LPS was added in the presence of IFN-γ and TNF-α. After 24 hours the cells were infected with decreasing amounts of infectious HCMV_TB40/E (MOI = 10, 5, 1, and 0) for 48 hours. Immunofluorescent labeling of DCs in each group was carried out, first with CyChrome-conjugated HLA class II antibody (MFI shown on Y axis), followed by intracellular staining of fixed and permeabilized cells with FITC-conjugated HCMV pp52 antigen, as described in “Patients, materials, and methods.” The numbers in the upper right quadrants represent HCMV Ag-positive, HLA class II positive cells. A representative of 3 repeated experiments is shown.