Another explanation could be that CXCL13 reflects the immune dysregulation and chronic inflammation in complex CVID, as evidenced by the abundance of hyperplastic yet inefficient germinal centres with the expansion of cTFh cells, first described by Unger et al. and then by Romberg et al. [57, 58]. The positive correlation we identified between serum CXCL13 and cTfh cells may reflect this phenomenon. This evidence concerns the gene CXCL13 and common variable immunodeficiency.