This is one of the newer drugs appearing on the bodybuilding scene that I would like to comment only briefly on. The human body produces several growth factors that are mediators and intermediates. In short this means they translate or decrease/increase the effect of hormones and other growth factors.
A study published in the Journal of Endocrinology in 1995 showed IL-15 doubled the rate of hypertrophy in skeletal muscle tissue. Interesting? Well the same study showed that stacking IL-15 with IGF-1 (insulin like growth factor-1; the stuff GH is converted into by the liver and other sites) increased muscular hypertrophy (excessive development/growth) by 500%. How is that for mediation? I have known only a few athletes whom have utilized this stack, and to be honest, I have always believed freaks can be created even from those with below average genetics anyway. Yes, the results were amazing. The down side of IL-15 use is that lack of research. Some have speculated that IL-15 can trigger cancer cell growth. However, available research has not shown a connection between IL-15 and organ growth as of yet. I will not, at this point, explain reported cycles or use. There is not enough research as of yet concerning possible negative side effects. However as more research becomes available, you can bet I will be happy to share the reported results.

*A note of serious interest. There is also an Interleukin-6 . DO NOT EVEN THINK ABOUT IT! It is used by AIDS patients as an immunocytochemical. This means it modulates an immune reaction to infection. It creates an inflammatory reaction and very high cortisol levels while suppressing IGF-1 and Androgen levels. So do not chase AIDS victims around asking for some. They have enough problems to deal with.