CXCL12 and synovial sarcoma: Interestingly, the lungs of both RA and SS patients with pulmonary disease have extraordinary increases in the expression of the chemokines, CXCL13 and CXCL12 (216), which likely contribute to the recruitment of lymphocytes and the formation of iBALT areas in the lung, comparable to what is observed in the salivary glands of SS patients (217).