Fig 3.

In vivo selection of red blood cell (RBC) expression γ-globin. Peripheral blood was collected from non-transgenic wild-type (WT) mice, WT mice containing a single copy of the γ^lo transgene alleles (γ^lo/−), and Hbb^th–3/+ thalassaemia mice containing a single copy of the γ^lo transgene allele, fixed and stained with a phycoerythrin-conjugated monoclonal antibody to HbF, and analysed on a flow cytometer. (A) Typical analysis showing the lack of staining in a non-transgenic control (no Tg; filled histogram), as well as the shift from a heterocellular pattern of γ-globin expression in a transgenic WT mouse (γ^lo/− WT; heavy line) to a pancellular and significantly elevated pattern of expression in a Hbb^th–3/+ mouse (γ^lo/− Thal; light line). The marker used to define HbF(+) is indicated. (B) Percentage of HbF(+) RBC in WT versus Hbb^th–3/+ mice containing a single copy of the γ^lo transgene allele showing a selective expansion of these cells in the thalassaemia background. Data represents mean ± SD for at least six individuals. (C) Mean fluorescence of HbF(+) RBC from panel (B), showing a concomitant increase in the intensity of staining in the thalassaemia background. *P < 0.01 vs. WT.