FLT4 and acute respiratory distress syndrome: In addition, they showed a significant decrease in VEGFR-3 expression and efferocytosis in human monocyte-derived macrophages upon incubation with bronchoalveolar lavage fluid from acute respiratory distress syndrome (ARDS) patients, suggesting that the protective function of macrophages is potentially impaired in patients during ARDS due to decreased levels of R3+ macrophages.