This is way above my level but a quick skim seems to suggest that not only are the cells not rejected, but that they can actually enhance the recipient's immune

This is way above my level but a quick skim seems to suggest that not only are the cells not rejected, but that they can actually enhance the recipient's immune system. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5532073/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5532073/