HCMV infection of immature and mature moDCs impairs their allogeneic stimulatory activity. MoDCs were infected with EC- or F-propagated HCMV strains. Controls included medium alone without virus or UV-inactivated virus (mock infection). At day 1 after infection, moDCs were added as stimulator cells to allogeneic T cells from a CMV-seronegative donor. T cells (10⁵ per triplicate U-bottomed well) were stimulated by different doses of moDCs in RPMI-10%NHS: (A) immature moDCs or (B) mature moDCs, both from the same donor and infected or not with EC strains, or (C) mature moDCs infected with F strains. Note y-axes use log₂ scales to depict T-cell proliferation based on 3HTdR incorporation (counts per minute [cpm]) during the last 8 to 12 hours of a 5-day culture. (D) Percent inhibition of proliferation in the allogeneic MLR at a given DC/T-cell ratio (1:100) correlated with the rates of infection (% IE1-positive cells of the total DC exposed to HCMV) of the immature (♦) or mature (○) moDCs. Note that the lowest rates of infection were in the 3% to 5% range. r indicates coefficient of correlation.