IL18 and synovial sarcoma: IL-18 has been linked to the severity of SS (Chen et al., 2016), inflammation (Baldini et al., 2013), parotid-gland enlargement (Tzioufas et al., 2012), and lymphoma (Ciccia et al., 2015), while IL-23 appears to promote differentiation of Th17 cells (Katsifis et al., 2009; Jin and Yu, 2013).