Detection of the T cell activation state using nonlinear optical microscopy.

Area of Science:

• Immunology
• Biomedical Optics
• Cell Biology

Background:

• Monitoring T-cell activation is crucial for immunotherapy efficacy.
• Existing T-cell activation markers have limitations in abundance and regulation.
• Third Harmonic Generation (THG) imaging has previously differentiated cell types based on lipid profiles.

Purpose of the Study:

• To investigate the potential of THG imaging for monitoring T-cell activation.
• To correlate THG imaging signals with specific biochemical changes during T-cell activation.

Main Methods:

• T-cells were stimulated using mitogens or antigens.
• Third Harmonic Generation (THG) imaging microscopy was employed for cell analysis.
• Raman spectroscopy was used to obtain chemical information and correlate with THG signals.

Main Results:

• Activated T-cells exhibited a statistically significant increase in THG mean area and intensity compared to resting T-cells.
• Raman spectroscopy revealed significant differences between activated and control T-cells.
• THG signal area correlated with cholesterol and lipid compounds, but not triglycerides, in activated T-cells.

Conclusions:

• THG imaging shows potential as a label-free method for assessing T-cell activation.
• Nonlinear microscopy, specifically THG imaging, could be valuable in clinical practice for immunotherapy monitoring.
• The lipid composition changes during T-cell activation are detectable via THG imaging.