Figure 5.
Co-expression of VEGFR-3 and VEGF-C in peritumoral stroma and in CD14 affinity-purified circulating human monocytes. In the peritumoral tissue, both VEGF-C (green channel) and VEGFR-3 (red channel) are co-expressed simultaneously by the same TAMs, and co-localize within the cytoplasm in a granular compartment, presumably in endosomes or lysosomes. By contrast, round CD14 affinity-purified monocytes express VEGFR-3 on their surface membrane, and in a perinuclear compartment, presumably the endoplasmic reticulum, but they do not express VEGF-C. The number of these CD14+ cells that express VEGFR-3 was determined in four different patients by fluorescence-activated cell sorting, and amounted on average to ∼60%. Incubation of these cells with exogenous VEGF-D and TNF-α induced de novo synthesis of VEGF-C. While incubated with VEGF-D (1 μg/ml, 30 minutes, 37°C) they remained round, TNF-α (50 U/ml, 30 minutes, 37°C) induced cell flattening and endocytosis of receptor-ligand complexes, similar to TAMs observed in vivo. Original magnifications, ×2500.