Effect of IL-15 on infection of NK-depleted PBMC by HHV-6. PHA-activated NK-depleted PBMC were infected with HHV-6 and cultured in the absence (A) or presence of 10 ng/mL (B) or 50 ng/mL (C) rIL-15. HHV-6 antigen expression and HHV-6 DNA content (D) were determined as described in Materials and Methods and as in the legend to Fig 1.