Abstract Background TRANSPIRE is a prospective 8-center study of lung injury after hematopoietic stem cell transplantation (HSCT) in children. Monocyte chemoattractant protein-1 (MCP-1, also known as CCL2) is a protein produced by hematopoietic cells associated with inflammation. A previous study described a role for MCP-1 in idiopathic pneumonia syndrome (IPS) after HSCT. It is unclear whether MCP-1 in BALF reflects levels in plasma or whether localized lung production occurs. Hypothesis We hypothesized that measurement of MCP-1 in BAL fluid (BALF) and/or plasma in acute lung injury patients after HSCT differentiates and informs the cause of lung injury. Methods We reviewed clinical data of 96 patients who underwent bronchoscopy for an acute pulmonary event after HSCT. BALF and plasma were collected. Pulmonary injury was diagnosed at the time of event by the attending pulmonologist. We recorded macrophage percentage from cytology reports. We measured soluble CCL2/MCP1 in plasma and BALF by ELISA (R&D Systems DCP00). Results There were 96 matched plasma and BALF samples from 90 patients (some patients had multiple events). Median age of participants was 10.3 years and median time from transplant was 37 days. Levels of MCP-1 according to clinical diagnosis are shown for BALF (Fig. 1A) and plasma (Fig 1B). Overall, levels of MCP-1 were higher in BALF than plasma. There is greater range in levels measured in BALF than plasma. Levels of MCP-1 in BALF and plasma are weakly correlated with each other (Fig 2). Our data show elevation of BALF MCP-1 in most patients with IPS not reflected in the plasma levels, but lesser elevation in BOS. We found no correlation between percentage of macrophages in BALF on clinical cytology. Levels of MCP-1 peripheral blood monocyte count was not correlated with MCP-1 in the BALF and has negative correlation with MCP-1 in blood. Conclusion Our data demonstrates differences in MCP-1 in patients with pulmonary injury that differ in BALF and plasma. MCP-1 levels were higher in BALF than plasma suggesting that MCP-1 is being produced in the lung. The main site of MCP-1 production is generally believed to be hematopoietic cells. Localized lung production, with increased MCP-1 levels in BALF have been described in normal humans and mice given inhaled LPS and with active inflammation. Our data support that this disease may be monocyte/macrophage driven, while BOS is largely neutrophil driven. Our data suggests value in examination of BALF and plasma in acute lung injury after HSCT. This abstract is funded by: TRANSPIRE
Strecker et al. (Fri,) studied this question.