 II. To determine the effects of the dose schedules of rhIL15 on the function of peripheral blood mononuclear cells including: T cell subset response to recall viral antigens including cytomegalovirus CMV and influenza A virus; T cell responses to non-physiologic stimuli including: phytohemagglutinin PHA; and NK cell cytokine interferon gamma IFN-y secretion and degranulation by cluster of differentiation 107a CD107a expression. 