CXCL13 and HIV infectious disease: Two other reports indicate that there are abnormalities in the CXCR5/CXCL13 system during HIV infection: first, Förster et al. reported some years ago that many recirculating mature B cells lose expression of CXCR5 during HIV infection; in contrast, these cells nearly uniformly express CXCR5 in healthy, uninfected, individuals [33].