To address this question, we sorted CD3+CD4+CD45RA+ naïve, CD3+CD4+CD45RA-ICOS- resting memory, and CD3+CD4+CD45RA-ICOS+PD-1highCXCR5+ total Tfh CD4 T cell populations from chronically HIV+ subjects (HIV+ITP+ n = 5) and quantified integrated HIV proviral genomes (Fig 5). This evidence concerns the gene ICOS and autoimmune thrombocytopenic purpura.