People with fibromyalgia have pain for no known reason. Camilla Svensson's group at Karolinska Institutet has discovered is that people with fibromyalgia have something in their blood that people without it are lacking, they have antibodies that seem to trigger the pain. Svensson's hypothesis is that they trigger the nerve cells, causing them to send constant pain signals.
This finding could mean that fibromyalgia will need to change its category. From pain where there is no physical explanation and where some are not even believed to pain that can be explained as a mis programmed immune system.