Virus-free CMV conditioned medium (CMV CM) suppresses monocyte oxidative activity. Purified primary monocytes were incubated with day 2 virus-free CMV and mock conditioned medium (CM). The day 2 CMV and mock CM (50 μL) was added together with 150 μL of medium. Every 2 days, 100 μL was removed from each well and replaced by 50 μL of CM and 50 μL of fresh medium. The oxidative assay was performed in triplicate, after 2, 4, 6, and 8 days. Results, presented as the mean ± SD of the OD values, are representative of two independent experiments. The boxes contain the percentage of oxidative activity inhibition (mean ± SD) corresponding to the ratio between the OD value obtained with HCMV and the mock preparation multiplied by 100.