Erm, I've had wine so this might not be very good bugs but I'll give it a go.
The theory is that NK cells if overactive can reject an embryo. An embryo is 50% your DNA, 50% foreign material, so if they go into overdrive, they don't allow an embryo to implant, treating it like a cell mutation (which your system should reject to stop it turning into something like a tumour), instead of an embryo.
Certain treatments and supplements can help supress/bring into balance the immune system. Main supplements are omega 3/6/9 and vit D3. Main drucks are prednisolne (a steroid), hydroxy-somethingorother (a malarial drug), intralipids (a drip) and other things like Humira that I don't know much about. The object of them all is to balance your immune system.
The big question mark is that a lot of drs doubt that testing the levels of NK cells in the blood tells you anything about the status of NK cells in the womb. Also, NK cells do useful things like fend of cancer mutations, so is it wise to mess with them?
I gave it all a go for 6 months, didn't get diffed, did get a dodgy smear, so I am a lot less convinced of the wisdom of fucking around with the immune system than I used to be. When I first heard about it, I thought I had explained our unexplainedness, now I am not so sure.
I'll lend you my copy of the dr beer book which puts it in rather more technical terms if you promise to send it back when you are done! PM me if you want it.
So I went to the pub for a quick one at 5.30 and have only just got in. Oopsie.