Label-free characterization of white blood cells by measuring 3D refractive index maps

TL;DR

This paper introduces a label-free method using 3D optical diffraction tomography to characterize white blood cells, providing detailed morphological and biochemical information without the need for cell labeling.

Contribution

The study demonstrates the use of 3D refractive index mapping via optical diffraction tomography for label-free, detailed analysis of WBCs, including their heterogeneity and phagocytic activity.

Findings

Successful 3D RI tomogram reconstruction of WBCs

Effective separation of WBC subpopulations based on morphology and biochemistry

Visualization of bead ingestion trajectories by WBCs

Abstract

The characterization of white blood cells (WBCs) is crucial for blood analyses and disease diagnoses. However, current standard techniques rely on cell labeling, a process which imposes significant limitations. Here we present three-dimensional (3D) optical measurements and the label-free characterization of mouse WBCs using optical diffraction tomography. 3D refractive index (RI) tomograms of individual WBCs are constructed from multiple two-dimensional quantitative phase images of samples illuminated at various angles of incidence. Measurements of the 3D RI tomogram of WBCs enable the separation of heterogeneous populations of WBCs using quantitative morphological and biochemical information. Time-lapse tomographic measurements also provide the 3D trajectory of micrometer-sized beads ingested by WBCs. These results demonstrate that optical diffraction tomography can be a useful and versatile tool for the study of WBCs.