Cytokine Bead Array
SF samples (n=17), matched serum samples (n=15) from SLE patients (Table 1), and SF samples from RA patients (n=10, Supplementary Table S1) matched for storage time, were analyzed with cytokine bead array (CBA) for T-helper-associated cytokines (BD Biosciences, San Jose, USA) following the manufacturer’s instructions. In brief, thawed serum samples were diluted 1:2 with assay diluent and run-in duplicates in a 96-well plate. Cytokines tested were IL-17A, IFNγ, IL-10, IL-6, IL-4, IL-2 and TNF. The assay was run on a FACS Verse flow cytometer and analyzed using the CBA software (BD Biosciences, San Jose, USA). Limits of detections are displayed in Supplementary Fig. S2C.