SELL and synovial sarcoma: We found that only three immune cells exerted independent effects for SS: CD27 on IgD+ CD24+ B cell (OR = 1.111, 95%CI 1.038–1.189, p = 0.002); CD80 on CD62L+ mDC (OR = 1.105, 95%CI 1.034–1.181, p = 0.003) increased the risk of SS; and CD38 on IgD+ CD38+ B cell (OR = 0.893, 95%CI 0.818–0.975, p = 0.011) reduced the risk of SS.