The role of the neutrophil in the development of ards

Abstract

We investigated the levels of various cell adhesion molecules (CAMs), 1CAM-1, LFA-1 beta, Mac-1, L-selectin, LFA-1 alpha, and VLA-4, found on white blood cells. Recruitment of neutrophils to the site of an immune response is dependent upon the expression of CAMs on the cell. In particular, the neutrophil was examined because of its proposed role in the development of acute respiratory distress syndrome (ARDS). The neutrophil is the first white blood cell summoned to a site of injury. To better understand results seen in patients at risk of developing ARDS, we first established normal control levels of the various CAMs. For each experiment, normal patients were used. Blood was collected at 1, 3, 6, 9, 12, 18, and 24 hour time points. Unstimulated and PMA-stimulated blood was examined at each time point. Addition of the primary antibody against the various CAMs was followed by the addition of the secondary antibody, FITC anti-mouse Ig. The cells were analyzed by flow cytometry to determine the fluorescence seen in the neutrophil cell population. Histograms showing level of fluorescence detected on the cells were then derived for the neutrophil population. A paired t-test was performed to compare the unstimulated and PMA-stimulated cells at specific time points. A significant difference was found in Experiment 1 for ICAM-1, Mac-1, and L-selectin but was not supported by data from the other two experiments. In Experiment 2, LFA-1 alpha exhibited a significant difference which was not supported by the other two experiments. Normal controls were also done to establish if diurnal variation occurred over time. The repeated measures one way ANOVA analysis was done to determine if a significant statistical difference had occurred. Statistical differences were only found in Experiment 1 which could be indicative of diurnal variation. However, this finding was not supported by the subsequent experiments. Future studies will examine the effect of CAMs in the development of ARDS. A better understanding of the role of CAMs in the onset of inflammatory responses may aid in the development of compounds able to modify the immune response and reduce the incidence of tissue injury.