Hi MurrayCod
After trying for 2.5 yrs (unexplained infertility) I have just this month been diagnosed with abnormally high NK cells as well. My FS gave me some of the research articles from the medical literature on NK cells. There are mixed views on the role of NK cells in infertility and miscarriage. However, the literature is pretty clear that Prednisolone does reduce the number of NK cells. In addition there was an article about a very perservering UK woman who after 19 miscarriages was treated for high NK cells with Prednislone and had her first child.
The very best of luck to you.