Monocyte production of sVEGFR-1 is dependent on JAK2/STAT5 signaling. (A) Human peripheral blood monocytes were treated with the JAK2/JAK3 inhibitor, AG490, before stimulation with GM-CSF at ambient O2 or 0.5% O2. Cell-free culture supernatants were collected after 48 hours and analyzed for sVEGFR-1 content by ELISA. (B) VEGF levels under the same conditions as in panel A. (C) Human peripheral blood monocytes were stimulated with GM-CSF for 5 minutes at ambient or 0.5% O2, and levels of p-STAT5 (Y694) were measured by flow cytometry. The shaded peak represents the staining of the isotype control. Results from a representative donor are shown. (D) Monocytes were stimulated with GM-CSF at ambient O2 or 0.5% O2 for various lengths of time (5 minutes to 48 hours), and p-STAT5 levels were measured by flow cytometry. Data are expressed as the percentage of positively stained cells at the indicated time points. All results represent the mean ± SEM of 4 normal donors.
