Neutrophils are implicated in the pathophysiology of multiple asthma phenotypes. It was shown in study IST Q4935s that low-density granulocytes (LDG) are elevated in the blood of patients with moderate or severe asthma. The greatest frequency and the highest percentages of LDG were observed in subjects with severe asthma. The LDG, which were first identified and characterized in systemic lupus erythematosus (SLE) patients, have been reported to display increased cytotoxicity for endothelial cells, increased tendency to form neutrophil extracellular traps, and increased production of tumor necrosis factor (TNF). It was also observed that the LDG expressed increased levels of CD15, which can facilitate attachment of activated platelets to the LDG. Identification of a putative serum biomarker that correlates with increased levels of the CD15+ LDG may be useful for the detection of neutrophil-associated inflammation in severe asthma.
Thirty subjects will be screened to identify 20 subjects with severe persistent asthma. The following data and/or samples will then be obtained within three weeks of the clinical assessment: (1) the percentages of LDG will be quantified by flow cytometry; (2) a blood sample will be collected into a PAXgene Blood tube and stored until shipped to Genentech for gene profiling analysis; and (3) a serum sample will be collected for measurement of total immunoglobulin E (IgE) and for future confirmation of potential biomarkers identified in the gene profiling analyses.
