Most of the vaccines etc have managed fron stem cells. Some stem cells are from aborted fetuses, but some are from placental. I don't know about the plasma therapy, but I'll look into it.
According to the makers of Regeneron, it is produced from epithelial cells, not aborted fetal cells.
See: https://www.dailywire.com/news/ben-carson-trump-saved-my-life-after-i-got-covid
Wrong link, sorry.
https://heavy.com/news/regeneron-monoclonal-antibodies-not-from-human-fetal-embryo-stem-cells/