Adhesion of subsets of human blood mononuclear cells to porcine endothelial cells

Cellular immune response is a major barrier to xenotransplantation, and cell adhesion is the first step in intercellular recognition. Flow-cytometric adhesion assay has been used to investigate the differential adhesions of monocyte (Mo), natural killer cell (NK) and T lymphocyte (T) present within human peripheral blood mononuclear cells (PBMC) to porcine aortic endothelial cells (PAEC), and to demonstrate the effect of human interferon-γ (hIFN-γ) or/and tumor necrosis factor-α (hTNF-α) pretreatment of PAEC on their adhesiveness for different PBMC subsets. The preferential sequence for PBMC subset binding to resting PAEC is Mo, NK and T cells, among which T cells show the slightest adherence; hTNF-α can act across the species, and augment Mo, NK and T cell adhesion ratios by 40%, 110% and 3 times, respectively. These results confirm at the cell level that host Mo and NK cells are major participants in the cellular xenograft rejection, thereby, providing a prerequisite for further studying the human Mo/NK-PAEC interactive mechanisms.