CXCR5 and synovial sarcoma: In order to more quantitatively interrogate all major CD4+ T cell subsets, including Th1, Th2, Th17 and Tfh cells, as well as regulatory T (Treg) cells and CD4+ cytotoxic T cells (CD4+CTLs), we performed multi-color immunofluorescence by labeling T-bet, GATA3, RORγ, CXCR5, Foxp3, and GZMA on LSG tissues from 13 patients with pSS and seven patients with secondary SS.