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need help in facs data analysis of surface expression - (Sep/04/2006 )

dear all
I am beginner in using facs. how to get the mean fluorescence intensity to compare two peaks ? on BD software is the mean fluorescence intensity of the drug treated sample determined from the the statistics menu by selecting numerator as the (drug treated sample) and dividing it on the (control vehicle treated sample) as the denominator? when I changed the denominator to (drug treated sample ) but keeping the numerator as (the drug treated sample) the value did not change is this logic?
comments are welcome


Hi yobou,
First of all cosidere two controll first one without treatment and second one with blank vehciles. Then analysised histograme of each samples by placing same markers(M1 and M2) according to samples without treatment then you gets in states information about mean , geo and
% of cells in different region this way you able to ploting these values and able to compired it.
I think you understand whats i want to explan you.
all the best and good luck.


I normally overlay my test peak over my control peak to look for a shift in flow cytometry. I'd compared the mfis directly with each other from the histogram statistics tables of separate plots (either M1 gated or ungated) rather than using a denominator etc. If the mfi increases expression is increased by treatment if it goes down expression is decreased. Sometimes it's better to look at increases/decreases in the % cells expressing or a gated population if you're effect isn't on the whole population but a proportion of the total number of cells.

I've basically said what Awadh has said I think.

All the best,


thanks for your comments. I have attached to this reply the calculation I made as PDF files. based on the results mentioned in those files can I conclude that my drug treatment increases the surface expression of my receptor of interest 2 folds?
looking forward to receiving your replies
thanks a lot