Percentage γ versus mouse age for 3 different types of mice.

Filled circles, percentage γ/all β-like chains by HPLC; triangles, percentage F-cells by FACS; squares, percentage γ by chain synthesis. Mice older than 180 days are plotted as 172 to 178 days; in this range, there was no correlation between percent HbF and age. Note that γ increases with age in all mice, but that the percentage γ/all β-like chains as measured by chain synthesis for NY1KO γM does not increase with age. The most dramatic changes in percentage γ occurred in mice with F-cells (both lines of mice expressing γM; bottom 2 panels). The largest difference between γ as measured by chain synthesis and by HPLC in peripheral blood was found in mice with F-cells. The increase in percentage γ in whole blood over percentage γ as measured by chain synthesis is due to increased survival of F-cells.