IL-2 induces an increase in EC permeability. A) IL-2 receptor α, β, and γ subunit levels as determined using RT-PCR. Lane 1: reference cDNA, lane 2: cDNA isolated from peripheral blood mononuclear cells, lanes 3–5: cDNA isolated from ECs from three different donors. Data are representative of five experiments with similar results. B) Expression of IL-2 receptor α, β, and γ subunits on the surface of ECs as examined using flow cytometry. Specific staining was compared with background staining using an isotype control antibody. Data represent three experiments with similar results. C) As a positive control, the effect of TNF-α (20 ng/ml) or vehicle [PBS] on EC permeability was measured by determining the flux of dextran across ECs 24 hours after treatment. D) ECs were treated with 100 IU/ml IL-2 or without [Vehicle: PBS], and the flux of dextran across ECs was measured 24 hours after treatment. Data in (C-D) are presented as mean + S.E.M. (n = 4 in each group), are representative of three experiments with similar results, and *p < 0.05 examined using ANOVA.