In April 2013, my NK cell function was 13 out of a range of 8 - 170 - I know, in the "normal" range but my doctor said no, that's low. In September 2015, it had gone up to 15 out of a range of 7 - 125. Last month, January 2018, it had gone up to 24 (!), range of 7 - 125. So that's quite a bit, and I'm pretty sure it's due to andrographis which I started taking just about a year ago. I don't have "proof" that it's the andrographis, but I would bet the farm (if I had a farm) that it is responsible for this increase. I noticed an immediate benefit when I started it. For years I've gotten sick with a sinus type infection every time I crash, and I would crash generally once a week, and it would take 10 --14 days to recover from the sinus problems so essentially I was sick almost all the time. Being sick got to be worse than the crashing. Every once in awhile I'd have a few days respite. When I was sick it was quite debilitating - it just really drained my energy though my outward symptoms were not severe. After starting the andrographis, I started getting much less sick and also recovering much more quickly. It's been a miracle herb for me. This is what I take: https://smile.amazon.com/Planetary-...pID=411gyDI-lML&preST=_SY300_QL70_&dpSrc=srch And, as you can see, it's very cheap! One a day helps me a lot, and if I get sicker than usual, I'll up it to 2 or 3 for a few days and add in some Echinacea and goldenseal and it works quite quickly. It's an immune modulator plus has antiviral and antibacterial properties. So when I remember every 4 or 5 weeks or so I'll stop it for several days or week.