PBMC isolated by Ficoll gradient centrifugation from control Biotinylated cRNA was synthesized from total RNA (Enzo; Farmingdale, NY) and processed according to the Affymetrix GeneChip Expression Analysis Technical Manual (Affymetrix; Santa Clara, CA). 57 samples: 5 pauciarticular PBMC, 15 polyarticular PBMC, 11 control PMBC, 6 JSpA PBMC, 5 pauciarticular SFMC, 10 polyarticular PBMC, 5 JSpA SFMC classified by course. Keywords = Control, peripheral blood mononuclear cell (PBMC)