- Pharmacokinetics study after the NK infusion to see how the body handles the cells. For this test, the number of NK cells in the blood are measured over time. This requires drawing about 1 teaspoon of blood at 15 minutes, 30 minutes, 1, 2, 4, 8, 12, and 24 hours after the infusion (day 1); then every 24 hours on days 2 through 7, then once on days 10, 14, and 21.