IL6 and synovial sarcoma: The cytokines tested included IL-2, IL-7 and IL-15, growth factors essential for lymphocyte function, the Th2 cytokines IL-4 and IL-13, reported to have increased serum levels in SS patients (Geskin et al., 2015), and IL-6 and IL-9, which have been implicated in CTCL pathogenesis (Olszewska et al., 2021; Vieyra-Garcia et al., 2016).