MPO and rheumatoid arthritis: Recent studies conducted by Dragomir et al. [29] have highlighted the importance of individual susceptibility and the remarkable similarities with immuno-serological profiles of rheumatoid arthritis in which the following are preponderant: an increase in the pro-inflammatory interleukins 1β and 6, myeloperoxidase, and activation of the complement system; cases where fragments of HA are found within some macrophage populations [29].