Light scattering by single immune cells
Our group is currently working on light scattering by single immune cells. We call our method IRAM, for Integrated Raman and Angular-scattering Microscopy. What we do is focus laser light (785 nm) on a series of single immune cells. We have two measurement channels: one records the “spray pattern” of light that scatters off of the cells within a large, forward-directed angular cone, and then other records the “rainbow” of light that inelastically scatters off in the backwards direction (this is called “Raman scattering”). The spray pattern tells you (with some modeling and approximations, of course) the characteristic size of organelles within the cell. The rainbow tells you the chemical content.
The plot on the above slide shows the result of taking IRAM data from 20 immune cells, called CD8+ T-cells specifically. Ten of them were exposed to a powerful stimulant, staphylococcal enterotoxin B (SEB), and ten were not. The x-axis reports protein & lipid content, as measured by the Raman channel of IRAM; the y-axis reports the size of scatterers. In the end, the IRAM system can tell the difference between these cells, even though the normal microscope view of the cells themselves didn't always show a change.