Alternatively, polyclonal bystander activation of non-specific and low affinity B cells by cytokines and growth factors (e.g. IFN-a, TNF-a, IL-4, IL-10, BAFF) and surface CD40L [42]–[43], which may be over-expressed in untreated HIV-1 infection [42], may also affect the selection process. This evidence concerns the gene TNFSF13B and HIV-1 infection.