What the heck is anti-cyclic citrullinated peptide antibody?

Good news from my doctor today. I have low levels of anti-cyclic citrullinated peptide antibody. Umm, what? Anyway, the gist is that I may have a form of Rheumatoid Arthritis that is not going to aggressively damage my bones. This is a huge relief. I can deal with the daily medications and the occasional painful flare-up. But I was getting scared about what kind of permanent damage was happening and the possibility of future knee or wrist surgeries. I may have dodged a bullet here. Still waiting to see if the new medication is working yet. Tomorrow I have to start cutting back on the steroids until I get to the point where I feel pain again. Wish me luck.