Endothelial cell early activation induced by allogeneic lymphocytes in isolated perfused mouse lung

The early inflammatory response induced following vascularized organ allotransplantation is mediated by adhesin-ligand interactions between blood leukocytes and allogeneic endothelial cells. In the present study, we focused on the role of allogeneic blood lymphocytes in early immune alterations following lung reperfusion.

We developed an experimental model of isolated and ventilated lung in female C57BL/6 mouse perfused with either isogeneic (C57BL/6) or allogeneic (C3H/He) male mouse fresh blood for 3 hours. SRY DNA quantification by polymerase chain reaction (PCR) was used to assess the presence of perfusate cells in lung extract. Using quantitative reverse transcriptase (RT)-PCR, we measured mRNA expression both of the adhesion molecules--intercellular adhesion molecule (ICAM)-1, lymphocyte function-associated antigen (LFA)-3, vascular cell adhesion molecule (VCAM)-1, and endothelial leukocyte adhesion molecule (ELAM)-1--and of tumor necrosis factor (TNF)-alpha in lung tissue.

The number of blood lymphocytes is significantly decreased in allogeneic versus isogeneic condition at 3 hours of perfusion, without evidence of increased apoptosis or necrosis. In parallel, SRY DNA quantity recovered in the lung was 2.5 times higher in allogeneic condition, which was related to cells loosely adherent to endothelial cells. Lastly, the levels of mRNAs of all adhesion molecules and of TNF-alpha were significantly increased in allogeneic versus isogeneic conditions.

These results demonstrate that an early interaction between allogeneic blood lymphocytes and vascular endothelial cells is correlated with a high mRNA expression both of adhesion molecules and of TNF-alpha in the perfused lung. Our model of a mouse lung perfused with fresh blood appears to be a useful clinical assessment system for in-depth investigation of early cell activation and the resulting intragraft immune alterations.