NK Assay

David Peritt Peritt_d at a1.mscf.upenn.edu
Thu Feb 16 13:34:31 EST 1995

Subject: NK Assay
From: nuusers, nubenne at nurs.indstate.edu
Date: Wed, 15 Feb 1995 20:52:31 GMT
In article <nubenne.3.2F42698E at nurs.indstate.edu> nuusers,
nubenne at nurs.indstate.edu writes:
>I am working on a study which uses the standard CR51 release NK assay as
>outcome measure. The intervention is probably going to produce a very
>effect size, and I (and my advisor) am concerned that the day to day 
>variability in the NK assay itself may obscure any effect from the 
>intervention. It has been suggested that we try freezing the K562 target 
>cells in lots at the start of the study, to attempt to syncronize the 
>growth cycle of the targets to reduce variability related to target cell 
>changes in culture. Does anyone out there have any information
>NK assay reliability or use of the suggested method?
>Mary Bennett
>Nubenne at nurs.Indstate.Edu
>Indiana State University

We conduct NK assays often using various targets and have never worried
about the target variability.  These cells have been in culture so long
that all instabilities have been worked out.  Whether cycle differences
will matter has not bothered us much.  We try to use cells in log phase
growth for labeling.  The assay will be very variable in terms of label
taken up, time of exposure, temperature, CO2 etc.  To correct for these
you always have a spontaneous release and max release (we use tween). 
Then you calculate the % 51Cr specific release.   
(CPM-spont)/max-spont*100.  This clears up most of the improtant
variables in the assay.

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