*4.2. Juvenile Idiopathic Arthritis*

There are only a few papers on circulating MPs in other joint inflammations. In a recent study with 26 children with JIA, Kumar et al. found a greater number of PMPs in plasma of patients with the active disease compared to the patients with disease remission [55] despite the absence of a difference in the number of platelets. Additionally the number of PMPs in synovial fluid in JIA was close to the number of PMPs in serum of individuals with active disease. The researchers suggested the potential usability of PMPs determination as a sensitive indicator of JIA activity. As in the study by Knifjj-Dutmer et al. [49], the number of PMPs in patients with the active disease did not correlate with the number of circulating platelets, ESR and CRP. Boilard et al. [8] analyzed samples of synovial fluid in JIA patients and found an increased number of PMPs in synovial fluid of patients with JIA, whereas the number of PMPs was not determinable in synovial fluid of 95% of patients with osteoarthritis.
