Sensitivity of CyTOF vs. Fluorescence Cytometry
We are often asked about the sensitivity of CyTOF relative to conventional flow cytometry. It is a complex question, because, like flow cytometers, the CyTOF has label bias: it detects some isotopes with greater sensitivity than others. This is a factor of the detector mass window, with maximal sensitivity in the upper-middle portion of that window (peaking around AM 168-170 on the CyTOF 1). However, the ratio of highest to lowest sensitivity isotope is only about 3-4; while in conventional flow cytometry, fluorochromes can vary more than 10-fold in brightness. Of course, there are also many different types of flow cytometers, with differing sensitivities for any given fluorochrome. Nevertheless, we can summarize the situation as follows:
- -There is no mass channel as sensitive as PE (generally the brightest fluorochrome on a conventional flow cytometer)
-That said, there are about 40 CyTOF channels available, and all are better than the dimmest fluorochromes
-The use of multiple markers in CyTOF can partially overcome lack of resolution of a population using any one marker (but this may require multidimensional analysis, not sequential gating of 1- or 2-dimensional plots)
-Antibodies that are dim in fluorescence are generally dim in CyTOF, and vice versa; though there are a few discrepancies that probably have to do with the conjugation chemistry of CyTOF polymers