Expression of VEGF by human monocytes and CD4⁺ T cells.

CD14⁺ monocytes and CD4⁺ T cells were purified from human PBMCs. (A) VEGF expression in resting monocytes and in monocytes following activation by plastic adherence or treatment with sCD40L (Ancell, 10 μg/mL) or LPS (1 μg/mL) for 5 hours illustrate a marked induction in VEGF expression following stimulation with sCD40L. (B) VEGF expression in resting CD4⁺ T cells, and CD4⁺ T cells stimulated for 5 hours with sCD40L (Bristol Myers Squibb), PHA (1 μg/mL), or PHA in combination with either sCD40L, IL-4 (500 U/mL), or IL-12 (10 ng/mL). As illustrated, there is a low-level expression of VEGF in resting CD4⁺ T cells, and expression is markedly induced in PHA-activated CD4⁺ T cells. Treatment with sCD40L, IL-4, or IL-12 does not further enhance this effect. Treatment with IL-4 or IL-12 alone failed to induce any VEGF expression above baseline (not shown). The expression of VEGF in a renal carcinoma cell line is illustrated as a positive control (Control), and the expression of L32 and GAPDH serves as internal housekeeping gene controls. The expression of IL-2 and IL-4 is also illustrated. For both monocytes and CD4⁺ T cells, similar results were obtained with both sources of sCD40L. Representative autoradiographs of 3 experiments.