Question about MFI

Vinko Tosevski vinko.tosevski at
Sat Jun 16 14:19:14 EDT 2007

Dear all,

I am a young PhD student from Croatia and I have limited experience in the
flow cytometry. Most of my knowledge comes from textbooks and other
literature available to me (manufacturers protocols and instrument guides,

My problem lies in the fact that people in my department use cytometry every
day but know very little about the technique, the minimum needed to do their
work. Sometimes I feel they are misusing cytometry and I am afraid since
they supposed to be the people I should learn from.

So, if you'd be so kind to answer me a couple of questions:

1) What is the physical significance of MFI value (mean fluorescence
intensity)? What does it represent?

2) How does an analysis software calculate MFI value? What is the formula
for that?

3) In which situations is it recommended to express MFI values when
presenting cytometry results?

4) Is it allowed to do mathematical calculations with MFI values? I saw
couple of my coleagues deducing MFI values of isotype control from MFI
values of the sample?!? It makes no sense to me... What would be the
physical meaning of the resulting number?

I desperately need answers and I hope you'll find enough time to help me.

Vinko Tosevski

Vinko Tosevski, MMolBiol

Research and Teaching assistant,
Department of physiology and immunology,
Faculty of Medicine,
University of Rijeka,
Ulica brace Branchetta 20
HR-51000 Rijeka, Croatia

Tel: +385 51 651 192

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