CD27 and synovial sarcoma: This analysis confirmed that in our cohort of SS patients the frequency of circulating CD27− naïve B cells was increased compared to HD (mean±SD 68.5±16.0% versus 45.8±6.7%, respectively), whereas the frequency of CD27+ switched (6.0±5.2% versus 17.5±8.1%) and unswitched (4.9±6.6% versus 20.6±2.4%) memory B cells was significantly reduced (Fig. 1B, including p values).