Quantitative analysis of endotoxin-induced inflammation in human lung cells by Chipcytometry

Chipcytometry is a tool that uses iterative staining cycles with multiple antibodies for a detailed characterization of cells. Cell recognition is based on morphological features. Cells fixed on microfluidic chips can be stored and shipped enabling a centralized analysis, which is important for assessments in multi-center clinical trials. The method was initially implemented for the analysis of cells from peripheral blood. We adapted it to more heterogeneous human lung cells from bronchoalveolar lavage (BAL) fluid and induced sputum (IS). We aimed to assess the performance of Chipcytometry to detect and quantify the endotoxin induced inflammatory response in healthy subjects. BAL and IS samples of 10 healthy subjects were collected prior to and following segmental and inhaled endotoxin challenge. Samples were analyzed by Chipcytometry and were compared with flow cytometry, and differential cell count (DCC). Chipcytometry clearly detected the endotoxin induced inflammatory response which was characterized by a massive increase of neutrophils (BAL: 2.5% to 54.7%; IS: 40.5% to 71.1%) and monocytes (BAL: 7.7% to 24.7%; IS: 8.0% to 14.5%). While some differences between detection methods exist, the overall results were comparable. The ability of Chipcytometry to verify fluorescent signals with morphological features improved the precision of rare cell analysis such as of induced sputum lymphocytes. In conclusion, Chipcytometry enables the quantitative analysis of cells from BAL fluid and IS. Advantages over DCC and flow cytometry include the storage of cells on chips, the ability for re-analysis and the mapping of surface marker binding to morphological information. It therefore appears to be a promising method for use in clinical respiratory drug development.