Viral infection of the vascular wall cellular elements is involved in development of several pathophysiological events, including vasculitis, transplant rejection, and atherosclerosis. Previously, we have shown that cultured human vascular endothelial cells (ECs) may be effectively infected with herpes simplex type I virus (HSV-1), and this cultural model could be a useful tool for the explanation of many aspects of viral disease. In this study, we investigated the effects of conditioned media (CM) of peripheral blood mononuclear cells (PBMCs) on HSV-1 reproduction and cell adhesion molecule expression in cultured ECs. PBMC-CM induced the delay of virus reproduction or inhibition of virus reproduction. Effects of CM correlated with multiplicity of infection used for EC, time of PBMC contact with infected and glutaraldehyde-fixed endothelium, and the level of IFNs and cytokine production. Passages of and CM-treated and infected cells without signs of virus reproduction were, sometimes, followed by virus reactivation. However, at a low level of infection of CM-treated ECs the virus reactivation was not observed even after 2-3 cell passages. Neutralizing antibodies against IFN-alpha, IFN-gamma, and TNF-alpha, used separately or together, significantly abrogated the delaying and/or inhibiting action of CM. Additionally, PBMC-CM significantly increased the expression of ICAM-1 and VCAM-1 on cultured ECs. The strongest cell activation was induced by CM obtained from PBMCs co-incubated with virus-infected endothelium. Obtained results suggest that primed leukocytes produce soluble factors with either anti-viral or pro-inflammatory activity, and the effect of PBMC-CM may have a bi-directional action. On the one hand, due to production of interferons and several cytokines CM sets up HSV-1 latency or virus elimination from cultured cells. On the other, the same cytokines act on infected and/or neighboring ECs and initiate the cascade of inflammatory reactions in the vascular wall.