Analysis of signal transducers using flow cytometry is useful for detection of contractive and fluctuating signals

Investigation of signal transduction mechanisms is important for development of therapy and understanding complex life systems. In this study, to establish a novel recognition method of signal transduction pathways, we investigated signal transducers using flow cytometry. The flow cytometric measurement shows a mean phosphorylation level (mean of fluorescence intensity, MFI) and a deviation of the phosphorylation level (coefficient variation, CV) in a cluster of cells. As a model of signal pathways, Jurkat cells (T cell leukemia cell line) were stimulated with interleukin-21 or interferon-α, and signal transducers and activators of transcription (STATs) and extracellular signal-regulated kinase (ERK) 1/2 were measured using flow cytometry. Furthermore, peripheral blood was stimulated, and then various signal transducers of the lymphocytes and neutrophils were analyzed with MFI and CV. After the stimulation, the increase of STATs MFI induced a temporal change of CV. On the other hand, the decrease of ERK1/2 phosphorylation accompanied the sustained increase of CV. Finally, we classified the signaling characters into five types using a combination of MFI and CV. These findings contribute to an explanation of the known relationship between signal transducers and stimulants on each cell subset. Therefore, this method may be useful to discover a causal relationship between stimulants and signal transducers in complex systems