Effects of IL-15 on infection of PBMC by EBV. PBMC from 3 healthy blood donors were infected with EBV and cultured in the absence or presence of 25 to 50 ng/mL rIL-15. On days 7 and 10, the percentages of EBV-infected cells were determined using the ACIF test, with the use of a human reference serum. Results were calculated after counting a minimum of 500 cells. *P < .05.