TSP-1 down-regulates expression of VEGF-C in macrophages via CD36. Relative expression of VEGF-C (A, B, D, and E), VEGF-D (F), and VEGF-A (G) message and VEGF-C protein (C) in thioglycollate-elicited macrophages from WT or CD36^−/− mice: (A) freshly harvested, (B–G) cultured in the absence or presence of TGFβ2, TSP-1, or CD36 blocking and control peptides. Total RNA harvested from macrophages was subjected to real-time PCR analysis to detect expression of VEGF-C, VEGF-D, and VEGF-A mRNA and to detect VEGF-C protein culture supernatants were analyzed by ELISA. Although freshly harvested CD36^−/− macrophages express significantly lower levels of VEGF-C compared with WT controls (A) these macrophages retain their ability to respond to exogenously provided TGFβ2 in culture by increasing expression of VEGF-C (both message [B] and protein [C]) compared with WT controls. Inhibition of VEGF-C expression detectable in WT macrophages cultured with TSP-1 (5 µg/ml) is not detected in similarly treated CD36 ^−/− macrophages (D). In the presence of CD36-binding TSP-1–derived peptide capable of blocking CD36–TSP-1 interaction (CD36 blocking peptide), the inhibitory effect of TSP-1 on the VEGF-C expression in WT macrophages is significantly reversed (E). Treatment of WT macrophages to TSP-1 also inhibited the expression of the lymphangiogenesis factor VEGF-D (F), but not that of predominantly hemangiogenic factor VEGF-A (G). Expression of VEGF-C, VEGF-D, and VEGF-A relative to the GAPDH in four independent PCR reactions per RNA sample is indicated. *, P < 0.05 compared with WT, untreated or indicated control. Error bars indicate SD.