PDCD1LG2 and HIV-1 infection: On the other hand, and in view of the emerging role that GC B cells appear to have in providing differentiation signals (ICOS-L and PD-L2) to Tfh cells it cannot be firmly ruled out that damage induced by HIV-1 in the homeostasis of B cells may become a driving force for declined levels of Tfh cells during HIV-1 infection.