Investigation of interleukin 2 receptors on human endothelial cells.

We have demonstrated that both recombinant and purified IL-2 exert a direct effect on quiescent human microvascular endothelial cells in vitro, causing the cells to enter the cell cycle and proliferate (Hicks et al., 1989). In this study we have identified IL-2 receptors (R) on both human umbilical vein (HUVEC) and neonatal foreskin (HCEC) endothelial cells. The techniques used to identify the receptors included proliferation studies, flow cytometry and immunofluorescence. Results indicate that both HUVEC and HCEC possess low numbers of receptors since both cell types proliferate in response to IL-2. The number of receptors on the cell surface vary according to passage number and culture conditions. Immunofluorescent studies show discrete areas of staining on the cell membrane. These combined results suggest that human vascular endothelial cells possess IL-2R.