IL15 and Increased total leukocyte count: The long-term effects of recombinant human IL-15 (rhIL-15) have been studied in non-human primates, demonstrating that daily administration of IL-15 for 8-14 days resulted in lymphocytosis and leukocytosis, and white blood cell count returned to normal after discontinuation of IL-15 on day 28 in these studies [32].