Calman, I absolutely agree. The same type of bias can be introduced in subtracting out instrument noise since this is essentially instrument specific it would allow for huge interlaboratory variation. For this reason we always report the raw values without subtraction based on the Quantum Simply Cellular system. However, if a low cell control can be standardized to reference the low end as well as a high end cell control than these values should be valid for subtraction. Currently such a control does not exist. Stephen P. Perfetto, MS.,MT. (ASCP) Walter Reed Army Institute of Research Department of Molecular Diagnostics and Pathogenesis 1600 East Gude Drive Rockville, MD. 20850 _______________________________________________________________________________ Subject: MESF and correcting for isotype matched controls From: Calman Prussin <CPRUSSIN@niaid.nih.gov> at Internet_Gateway Date: 1/6/00 11:42 AM We are quantitating cell associated antigens using standardized beads and then generating an MESF from the standard curve generated from the beads. The question has come up whether or not to "correct" the MESF values obtained from the specific antibody by subtracting the MESF values obtained for the isotype matched controls. The problem with correcting the values is that it has little effect on the samples with high density of Ag, but has a large effect on those with low expression. As such, if we run replicate samples on the low expressing samples we find a larger amount of variation in the corrected MESFs. My bias is not to use it, as it seems to introduce more "noise" into the system. Your thoughts? Thanks! > _______________________ > Calman Prussin > Laboratory of Allergic Diseases > NIAID/ National Institutes of Health >
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