Label-free molecular imaging of immunological synapses between dendritic and T cells by Raman micro-spectroscopy

Analyst. 2010 Dec;135(12):3205-12. doi: 10.1039/c0an00508h. Epub 2010 Oct 18.

Abstract

Confocal Raman micro-spectroscopy (CRMS) was used to measure spectral images of immunological synapse formation between dendritic and T cells without using molecular labels or other invasive procedures. The purpose-built inverted CRMS instrument integrated an environmental enclosure and a near-infrared laser to allow measurements on live cells maintained under physiological conditions. The integration of the wide-field fluorescence also enabled viability assays and direct comparison between Raman spectral images and gold-standard immuno-fluorescence images for specific molecules. Raman spectral images of nucleus and proteins were built by fuzzy c-mean clustering method. The Raman images were found to be in good correspondence with the immuno-fluorescence images of DNA and actin. These results indicate that actin is a main contributor to the Raman spectrum of the cytoplasm of dendritic and T cells. While for control cells the Raman spectral images of proteins indicated a more homogeneous distribution of proteins in the cytoplasm of dendritic cells, they indicated a higher accumulation of proteins at the immunological synapses when dendritic cells were pre-treated with laminin. These conclusions were also supported by confocal immuno-fluorescence imaging after cell fixation and labelling. This study demonstrates the potential of CRMS for label-free non-invasive imaging of junctions between live cells. Therefore, this technique may become a useful tool for studying cellular processes in live cells and where non-invasive molecular specific imaging is desirable, such as cell-cell interactions.

Publication types

  • Evaluation Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Actins / chemistry
  • Cells, Cultured
  • Cluster Analysis
  • Coculture Techniques
  • Dendritic Cells / chemistry*
  • Dendritic Cells / ultrastructure
  • Humans
  • Immunological Synapses / chemistry*
  • Immunological Synapses / ultrastructure
  • Laminin / chemistry
  • Microscopy, Confocal / methods*
  • Spectrum Analysis, Raman / methods*
  • T-Lymphocytes / chemistry*
  • T-Lymphocytes / ultrastructure

Substances

  • Actins
  • Laminin