Re: autofluorescence & isotype control fluorescence

From: Olindo Assis (oamfilho@netra.cpqrr.fiocruz.br)
Date: Mon Oct 23 2000 - 06:56:15 EST


Dear Karim,

I really like your question. First because I see a lot of people stating
that in cases of autofluorescence we should adjust the voltage for
fluorescence on the cytometer in order to bring the negative (isotype
control) to the first decade. In another words, people tend to perform
instrument settings using their own cells regardless the autofluorescence
component.

I disagree with that since I always recommend my students to set the
instrument using a calibration system (like CaliBrite form BD, or other
available).

As far as your question, I would take the first alternative, based on the
results you present. However, it can also be result of a low expression of
the marker X and in this case to take the 9īs question (to confirm the
hypothesis) I suggest you to use a more sensitive fluorochrome, such as PE
or Cy-5, in a biotin-Streptavidin system to increase the sensibility of your
test. I have experience working with eosinophils, neutrophils, monocytes
from in vitro culture and PFA-fixed T. cruzi epimastigotes, which show high
autofluorescence. However, I always find then to shift to a higher MFC (mean
fluorescence channel) when they express any X marker I am looking for.

I hope it helps. Thank you for sharing your experience.


Best regards,

Olindo Assis



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