Figure 1. Induction of apoptotic cell death by HEMA. (A) HEMA at different molar concentrations was added to untreated and IL-2 (500 u/mL)-treated PBMCs (5 x 10⁶ cells/mL) for 12–18 hrs at 37°C. Propidium iodide (PI) at a final concerntration of 30 µg/mL was added to each sample, and the proportion of the PI stained cells was determined by flow cytometric analysis. The average and the standard deviation are shown for 10 separate HEMA-treated samples from healthy control donors. The two-tail unpaired p value for the difference between HEMA-treated and untreated samples at 0.082 M and 0.0164 M concentrations is less than 0.0001. (B) PBMCs were treated with different concentrations of HEMA, TEGDMA, and DNCB for 12–18 hrs. The levels of DNA strand breaks, indicating apoptotic cell death, were determined by the TUNEL assay. The cursor was set based on the staining obtained by control non-treated peripheral blood mononuclear cells. The events to the right of the cursor represent positive staining for apoptosis for each of the chemical treatments. One of three representative experiments is shown in this Fig. (C) PBMCs were treated with different concentrations of HEMA and CDDP for 12–18 hrs. The levels of apoptotic cell death were determined by dual staining with PI and annexin V. The numbers in each quadrant represent the percentages of cells positive for that quadrant. Ten thousand events were analyzed for each sample.