Mass Cytometry

By using metal isotopes to conjugate individual antibodies (instead of fluorophores), many more (>40) antigens can be labeled and measured at single cell resolution. Instead of measuring light, isotopes are identified via their time-of-flight (depending on atomic mass), with each isotope showing a distinct (non-overlapping) trajectory. This allows us to gleam a 'birds eye view' of virtually the entire immune system in action. This procedure is done using a machine which combines inductively coupled plasma mass spectrometry and time-of-flight spectrometry (a.k.a. CyTOF). 

Credit: Holden T. Maecker, PhD - Stanford University

Credit: Holden T. Maecker, PhD - Stanford University

Proposed workflow for investigating the effects of deep brain stimulation on immunity. (1) DBS stim (2) blood draw. (3) After CyTOF cells are gated and (4) dimensionality is reduced. (5) Cell types identified (T-cell example), and (6) further classified, and (7) expression of intracellular signaling pathways are examined. (image: JCB).

Proposed workflow for investigating the effects of deep brain stimulation on immunity. (1) DBS stim (2) blood draw. (3) After CyTOF cells are gated and (4) dimensionality is reduced. (5) Cell types identified (T-cell example), and (6) further classified, and (7) expression of intracellular signaling pathways are examined. (image: JCB).

Deep brain stimulation

How does the brain influence the immune system? Anecdotally, we know that it does; stress or fatigue can exacerbate sickness or promote disease development, and placebo drugs or meditation seem to actually 'work' to some degree. Exactly how discrete parts of the brain modulate immunity remains largely unknown. 

Monocytes

JCB whole blood stim.PNG

CD4+ T-Cells

JCB whole blood stim CD4.PNG

Intracellular protein expression in my own blood monocytes (top panel) and CD4+ T-Cells (bottom panel) after no stimulation (Green Line), LPS stimulation (Orange Line), or interferon-alpha stimulation (Blue Line). All of these measures (and many many more), can be gleamed simultaenously at the single cell level using CyTOF. Intracellular signaling proteins noted above are pCREB, STAT5, p38, STAT1, and STAT3, with each antibody tagged with a different isotope. Note the differences between cell types in LPS and IFN-alpha stimulation responses (credit JCB).

To investigate the brain-immune connection in unprecedented detail, we've decided to combine the mass cytometry approach with deep brain stimulation (DBS). DBS is used in a wide variety of disorders, where a stimulator is implanted in discrete brain regions to relieve or eliminate symptoms. 

I am currently part of an exciting project, where human patients that have deep brain stimulation implants in different parts of their brains have agreed to provide us multiple blood samples to investigate this question. By collecting samples before and after stimulations, we can understand how activation of specific parts of the brain alters whole-body immunity.

Banner image: Fluidigm