Development in the Context of the Cell Cycle
Thymocyte maturation can be monitored by following expression of the CD4 and CD8 surface markers. As thymocytes mature, they progress sequentially through:
- Double negative (CD4-/CD8-)
- Double positive (CD4+/CD8+)
- Singe positive (CD4+/CD8- or CD4-/CD8+)
Experimental Setup
Thymocytes from wild-type and mutant mice are labeled with a fluorescein-conjugated antibody to CD8 and an R-phycoerythrin-conjugated antibody to CD4. Labelled thymocytes are then subjected to flow cytometry analysis to determine CD4 and CD8 expression.
Flow Cytometry Results Interpretation
In the graphs shown, each dot indicates the CD4 and CD8 expression levels for a single cell. The cell populations are divided into quadrants:
1) Lower Left: CD4-/CD8- (double-negative)
2) Upper Right: CD4+/CD8+ (double-positive)
3) Upper Left: CD4+/CD8- (single-positive)
4) Lower Right: CD4-/CD8+ (single-positive)
The numbers in each quadrant represent the percentage of cells in that quadrant (mean 6 SEM). As shown, the more mature CD4 and CD8 single positive populations are expanded in the E2F-1 -/- mice. The experiment shown represents duplicate measurements from one pair of mice and is representative of seven experiments comparing in total 13 wild-type to 13 E2F-1 -/- mice.