CXCL13 and neoplasm: Notably, recruited B cells also generate CXCL13, which creates a positive feedback loop.43 After the constitution of the FDC network, FDCs become the main cells producing CXCL13 in GC.254 Tfh cells, in addition to B cells, express CXCR5 and migrate into the TLSs following the CXCL13 gradient, promoting GC maturation.119 Therefore, CXCL13 is often used as a marker for TLS formation and tumor prognosis.256 However, high levels of CXCL13 do not always indicate a favorable prognosis.