The aim of the present study was to assess the changes in cell membrane antigens on neutrophils from peripheral blood obtained from patients with pneumonia.
We obtained blood from twenty patients with pneumonia (16 men, four women; 67 ± 12 years of age). The expression levels of neutrophil membrane antigens were measured with a FACS caliber flow cytometer using several fluorescence-labeled monoclonal antibodies.
The expression levels of toll-like receptor 4 (TLR-4), a lipopolysaccharide recognition receptor, were higher in patients with pneumonia than in healthy individuals. In addition, the expression levels of CD64 (FcℽRI), an immunoglobulin G-binding receptor, were higher in patients with pneumonia than in healthy individuals. In contrast, the expression levels of CD11b and CD16 were lower in patients with pneumonia than in healthy individuals. The expression levels of tumor necrosis factor receptor (TNF-R) antigens were correlated with serum C-reactive protein concentrations. In addition, the expression levels of CD14, TLR-4, TLR-2, CD16, CD64, CD11b, TNF-R, and LFA-1 antigens were correlated with the ratio of immature neutrophils.
These results demonstrate that analyses of the surface antigens on neutrophils, which are strongly associated with biological defense or tissue injury, may be informative for understanding the pathology of pneumonia and for the development of new therapies targeting neutrophils.