Tc17 in ITP Figure 3. Correlations between Tc17 and Th17 cells in ITP patients and controls. (a, b) No significant correlation was demonstrated in newly-diagnosed (r = 20.3150, P = 0.1762) or CR ITP patients (r = 0.0773, P = 0.7017); (c) A positive correlation was shown between Tc17 and Th17 cells in controls (r = 0.7239, P,0.0001). doi:10.1371/journal.pone.0026522.g003 Figure 4. CD8 cells and CD4:CD8 ratio in ITP patients and controls. (a) Significant difference of the CD4:CD8 ratios between ITP patients (median, 1.42; range, 0.26–4.18) and control group (median, 1.90; range, 0.93–3.95; *P = 0.029). (b) Elevated percentage of CD8+ T cells in ITP patients (median, 29.34%; range, 9.78%–68.97%) compared with controls (median, 22.35%; range, 12.89%–32.3%; *P = 0.025). doi:10.1371/journal.pone.0026522.g004 [14],[15]. Tc17 and Th17 cells have also been shown to be infiltrated in positive patch test biopsy samples of patients with allergic contact dermatitis (ACD), indicating that Tc17 and Th17 cells are an integral part in the immunopathology of ACD, regardless of the nature of the triggering allergen [22]. Although Tc17 are aberrant in these autoimmune disorders, it is still not clear whether or not Tc17 are involved in ITP. To study the role of Tc17 in the development of ITP, Tc17 were examined in the peripheral blood of newly-diagnosed patients, ITP patients who achieved CR, and healthy controls. Our results demonstrated that the number of Tc17 (defined as CD3+CD8+IL-17+) was significantly increased in newly-diag- nosed patients, but not in patients who had CR, which indicated the importance of Tc17 in the development of ITP. Moreover, the PLoS ONE | www.plosone.org 5 October 2011 | Volume 6 | Issue 10 | e26522