This in vitro study was designed to characterize the molecular profiling of human endothelial cells (ECs) during the early phase of hypoxia-hypothermia (HH) conditioning and to evaluate their interactions with allogeneic monocytes. The HH-conditioned ECs were analyzed using real-time quantitative polymerase chain reaction (RT-PCR). A cell adhesion assay was performed to assess adhesion of purified allogeneic monocytes as well as CD4- and CD8-positive T cells to HH-conditioned ECs with or without blocking antibodies specific for CD15s and CD162. Uptake of EC membrane by monocytes with or without scavenger receptor blockade was examined using fluorescence-activated cell scanning. The RT-PCR revealed up-regulation of gene transcripts for inflammatory cytokines, monocyte-associated growth factors, costimulatory, and apoptosis-related molecules in HH-conditioned ECs. Analysis using fluorescence-activated cell scanning showed minimal CD54 up-regulation in HH-conditioned ECs. We noted low-level adhesion of CD4- or CD8-positive cells to resting and HH-conditioned ECs. High-level adhesion of monocytes to HH-conditioned ECs was observed when compared with resting ECs. Blockade of CD15s and CD162 dramatically reduced monocyte adhesion to normal and HH-conditioned ECs. Monocytes but not T cells showed uptake of EC membranes during their interactions with HH-conditioned ECs, which was inhibited by scavenger receptor blockade. These data characterized the molecular features of ECs during early HH-conditioning. The EC transcripts related to monocyte recruitment and interaction between monocytes and HH-conditioned ECs dominated the early post-HH condition. Blockade of CD15s and CD162 prevented monocyte adhesion to ECs. These findings suggest that the initial interaction between monocytes and HH-conditioned ECs has a central role during the early phase of reperfusion injury.