What's the deal with serum-free media?

So what's the deal with using serum-free cell culture media in one's immunology experiments?

I think this article says it all. Serum-containing media is loaded with all sorts of undesirable substances. This results in a high background response and more confused results. Furthermore, each serum-containing batch behaves differently, and characterizing each batch is both costly and time-consuming. Then of course, there are the infectious risks involved.

In contrast, serum-free media is cleaner and produces more consistent results. Serum does contain cell growth factors and essential nutrients, which means that developing the right substitute is a challenge. Having the right batch of serum-free media can really work wonders, though.