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Updated: Mar 29, 2026
Author Spotlight: Unveiling the Polyfunctionality and Heterogeneity in Immune Responses
Published on: March 8, 2024
T Cell Dynamic Activation and Functional Analysis in Nanoliter Droplet Microarray
Saheli Sarkar1, Vinny Motwani1, Pooja Sabhachandani1
1Department of Pharmaceutical Sciences, Northeastern University, 360 Huntington Avenue, Boston, 02115 MA, USA.
Insights
This study introduces a microfluidic droplet platform for analyzing immune cell responses. The technology reveals dynamic calcium signaling in T cells upon interaction with dendritic cells, highlighting heterogeneity in immune activation.
Area of Science:
- Immunology
- Microfluidics
- Cellular Biology
Background:
- Assessing immune response heterogeneity requires dynamic single-cell analysis and cell-cell interaction studies.
- Current methods struggle to dynamically investigate non-adherent cell interactions and paracrine signaling without interference.
Purpose of the Study:
- To develop and validate a microfluidic droplet microarray platform for simultaneous analysis of single T cell responses and heterotypic cell pair interactions.
- To evaluate the dynamic activation state of primary T cells using this novel platform.
Main Methods:
- Generation of monodisperse nanoliter droplets containing single human T cells or co-encapsulated T cells and dendritic cells.
- On-chip stimulation with ionomycin and dynamic calcium signaling monitoring.
- Co-culture of T cells with activated dendritic cells to observe cell-cell contact-dependent and independent signaling.
Main Results:
- Ionomycin stimulation induced heterogeneous calcium signaling fluctuations in T cells.
- T cells exhibited immediate calcium signaling upon contact with dendritic cells, indicating early activation.
- Delayed, non-contact mediated calcium signaling increases were also observed in T cells.
Conclusions:
- The nanoliter droplet array microfluidic platform enables dynamic assessment of cellular response heterogeneity.
- This technology facilitates the detection of early and delayed immune signaling events.
- It offers a promising approach for live cell phenotyping of immune cells.
Objective:
Characterization of the heterogeneity in immune reactions requires assessing dynamic single cell responses as well as interactions between the various immune cell subsets. Maturation and activation of effector cells is regulated by cell contact-dependent and soluble factor-mediated paracrine signalling. Currently there are few methods available that allow dynamic investigation of both processes simultaneously without physically constraining non-adherent cells and eliminating crosstalk from neighboring cell pairs. We describe here a microfluidic droplet microarray platform that permits rapid functional analysis of single cell responses and co-encapsulation of heterotypic cell pairs, thereby allowing us to evaluate the dynamic activation state of primary T cells.
Methods:
The microfluidic droplet platform enables generation and docking of monodisperse nanoliter volume (0.523 nl) droplets, with the capacity of monitoring a thousand droplets per experiment. Single human T cells were encapsulated in droplets and stimulated on-chip with the calcium ionophore ionomycin. T cells were also co-encapsulated with dendritic cells activated by ovalbumin peptide, followed by dynamic calcium signal monitoring.
Results:
Ionomycin-stimulated cells depicted fluctuation in calcium signalling compared to control. Both cell populations demonstrated marked heterogeneity in responses. Calcium signalling was observed in T cells immediately following contact with DCs, suggesting an early activation signal. T cells further showed non-contact mediated increase in calcium level, although this response was delayed compared to contact-mediated signals.
Conclusions:
Our results suggest that this nanoliter droplet array-based microfluidic platform is a promising technique for assessment of heterogeneity in various types of cellular responses, detection of early/delayed signalling events and live cell phenotyping of immune cells.
