With Paecs

NK cells have been shown to bind directly to the a-gal antigen and subsequently activate or disrupt PAECs. Thus direct interactions between NK cells and PAECs may play a role in endothelial activation and AVXR. While this interaction may be important in initiating AVXR it is enhanced by endothelial-bound xenoantibodies. The role of NK cells in pig-to-primate AVXR may be a transient one since they have been a rare finding in rejected porcine xenografts. NK mediated events are also not unique to AVXR since they are also seen in allogeneic models where they are not thought to play a major role. Direct interactions between monocytes/ macrophages and PAECs may also contribute to endothelial changes, although these interactions are also enhanced with anti-endothelial xenoantibodies. Furthermore, in all of these studies, the monocyte/macrophage isolation techniques used likely resulted in their activation, and therefore the results may not reflect de novo interactions between monocyte/macrophages and PAECs and thus are unlikely to represent initiating events in AVXR.

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