CCL21 and synovial sarcoma: For the anti-CCL21 antibody negative patients, the mean levels of CCL21 were 0.46 ± 0.53 ng/ml, 0.38 ± 0.19 ng/ml and 0.41 ± 0.22 ng/ml for SSc, SS and MCTD, respectively (Figure 7A).