Leukocyte function assessed via serial microlitre sampling of peripheral blood from sepsis patients correlates with disease severity

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Dysregulated leukocyte responses underlie the pathobiology of sepsis, which is a leading cause of death. However, measures of leukocyte function are not routinely available in clinical care. Here we report the development and testing of an inertial microfluidic system for the label-free isolation and downstream functional assessment of leukocytes from 50 μl of peripheral blood. We used the system to assess leukocyte phenotype and function in serial samples from 18 hospitalized patients with sepsis and 10 healthy subjects. The sepsis samples had significantly higher levels of CD16dim and CD16 neutrophils and CD16+ ‘intermediate’ monocytes, as well as significantly lower levels of neutrophil-elastase release, O2 production and phagolysosome formation. Repeated sampling of sepsis patients over 7 days showed that leukocyte activation (measured by isodielectric separation) and leukocyte phenotype and function were significantly more predictive of the clinical course than complete-blood-count parameters. We conclude that the serial assessment of leukocyte function in microlitre blood volumes is feasible and that it provides significantly more prognostic information than leukocyte counting.

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Fig. 1: Closed-loop inertial microfluidic separation of leukocytes from whole blood.
Fig. 2: Neutrophil subsets and function in sepsis and healthy patients.
Fig. 3: IDS of activated from non-activated human PMNs.
Fig. 4: Monocyte subsets in sepsis and healthy patients.
Fig. 5: Principal component analyses for routine CBC measures, clinical severity and leukocyte phenotype and function in sepsis and healthy patients.
Fig. 6: Correlation between PMN responses and measures of clinical severity during sepsis.

Data availability

The data supporting the results in this study are available in the Article and Supplementary Information. The raw patient data are available from the authors, subject to approval from the Institutional Review Board of Partner’s Healthcare.

Code availability

The custom code used in this study is available at https://github.com/bdlevylab/BDLevy-Lab.


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The authors acknowledge the contributions of G. Zhu, L. A. Cosimi and additional members of the Brigham and Women’s Registry of Critical Illness (including L. Fredenburgh, P. Dieffenbach, S. Ash and J. Englert). The work was supported by grant nos. U24-AI118656 (B.D.L., J.V.), K08-HL130540 (R.E.A.) and K12-HD047349 (M.G.D).

Author information

B.J., H.R. and D.-H.L. contributed equally to this study. J.H., J.V. and B.D.L. coconceived the study. B.J., H.R., D.-H.L., R.E.A., B.D.E., M.G.D., J.L., R.M.B., N.K., J.H., J.V. and B.D.L. designed the experiments and interpreted the results. B.J., D.-H.L., R.E.A., B.D.E, J.L., J.V. and B.D.L. performed and analysed the functional biological experiments. H.R. and J.H. designed and performed experiments using the inertial microfluidic system. A.H., M.P.-V., M.E.B. and R.M.B. provided blood samples and clinical data from patients with sepsis. The manuscript was written by B.J., H.R., D.-H.L., R.E.A., B.D.E., M.G.D., J.L., N.K., R.M.B., J.H., J.V. and B.D.L.

Correspondence to Bruce D. Levy.

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Jundi, B., Ryu, H., Lee, D. et al. Leukocyte function assessed via serial microlitre sampling of peripheral blood from sepsis patients correlates with disease severity. Nat Biomed Eng 3, 961–973 (2019) doi:10.1038/s41551-019-0473-5

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