PDCD1 and HIV infectious disease: A recent study looked at the role of pTFh, defined phenotypically as CD45RA− CCR7+ CXCR5+, in HIV persistence, they used an in vitro GFP reporter assay and found pTFh, in particular, PD1+ pTFh cells to be more permissive for HIV infection than non-pTFh cells (60).