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Clarification sought

Posted by lukesnell on 18 Jan 2012 at 22:30 GMT

Next, we characterized CXCR4 cell surface expression over time by FACS. In the R5-ZFN control group, with intact cxcr4 genes, 88% of CD4+ T cells expressed CXCR4 protein at day 27 post engraftment, compared to 84% of cells in the X4-ZFN mice (∼24% cxcr4 gene disruption) as determined by a fluorescence minus-one (FMO) control

I'm sure I'm probably misreading this. Why is the surface expression of CXCR4 so high (84%) in CD4 cells from X4-ZFN mice, which have been treated to disrupt CXCR4 expression? How does this correspond to a '~24% CXCR4 gene disruption'? This seems comparable with the control CD4 cells which have not had CXCR disrupted.

No competing interests declared.

RE: Clarification sought

cwilen replied to lukesnell on 24 Jan 2012 at 02:39 GMT

It is likely necessary to disrupt both CXCR4 genes in a given cell to prevent expression of detectable CXCR4 protein. Assuming a Hardy-Weinberg distribution, 24% total gene disruption would translate to about 5% of cells that have both CXCR4 genes mutated. This is relatively consistent with the reduction of CXCR4 protein positive cells seen (88% in the controls vs 84% in the X4-ZFN treated cells).

No competing interests declared.