TLOs commonly arise close to vascular or epithelial ductal structures adjacent to smooth muscle cells or myofibroblast-like cells that share features with conventional LTo cells, e.g., synovial fibroblasts from patients with rheumatoid arthritis display LTo-like properties, including expression of LTβR and the production of homeostatic chemokines (e.g., CXCL13) (129) and B-cell-activating factor (BAFF) to support synovial B cell responses (130), and LTβR signaling has been shown to induce aortic smooth muscle cells to form TLOs in atherosclerosis (71). The gene discussed is CXCL13; the disease is rheumatoid arthritis.