Figure 4.

Perforin expression is maintained in high affinity natural killer (haNK) cells in response to acute hypoxia. (A) Perforin expression as measured by flow cytometry in healthy donor (HD) NK and haNK cells incubated in 20% (gray) and 0% (blue) oxygen for 5 hours at 37°C. Inset: % positive cells (mean fluorescent intensity). (B) Cells were incubated as in (A) and perforin expression was measured by immunofluorescence (63×). Insets: average perforin positive staining cells positive per high power field; (right) secondary antibody control (40×). (C) ¹¹¹In-labeled prostate (PC3) cells were co-incubated with HD NK or haNK cells at 37°C for 5 hours under 20% or 0% oxygen. Lysis of target (PC3) cells was determined and used to calculate killing frequency (killing frequency=# target cells killed/# effector cells plated), a measure of the serial killing ability of NK cells. Results are normalized to HD NK at 20% oxygen. *P≤0.05 using Student’s t-test. This experiment was repeated two times with similar results.