Synovial fluid monocytes from patients with oligoarticular JIA had increased expression of the M1 marker CD40 (2452 vs 688, p < 0.001), CD86 (6414 vs 3247, p < 0.001), and the M2 marker CD206 (310 vs 88, p < 0.001), as compared to patients’ circulating monocytes (Fig. 1c). Here, CD40 is linked to juvenile idiopathic arthritis.