IL17A and rheumatoid arthritis: Menon et al. also demonstrated that IL-17+ CD8+ T cells are present at increased levels in psoriatic synovium when compared to paired samples of PsA peripheral blood and synovial samples from patients with RA, and that they are correlated to serologic (C-Reactive Protein and Erythrocyte Sedimentation Rate), clinical (Disease Activity Score 28) and imaging (power Doppler ultrasound score) features of PsA activity and erosive disease status (37).