CD8A and activated PI3K-delta syndrome: Using peptide-loaded HLA-A2 tetramers, virus-specific CD8+ T cells were analyzed from three APDS patients (EBV-specific CD8+ T cells), five HIV+ patients (HIV Gag- or Pol-specific CD8+ T cells, CMV-specific CD8+ T cells), and four healthy controls (EBV-specific CD8+ T cells).