Injection of the LvHA vector in the thymus of TCR-HA mice increases percentages and numbers of HA-specific Tregs. (A) Shown are the frequencies of HA-specific (6.5⁺) CD25⁺ within CD4SP cells (right panel) and CD25^– CD4SP cells (left panel) 1 to 2 weeks after intrathymic injection of LvHA or LvGFP lentiviral vectors in TCR-HA mice. Each dot represents individual mice from 3 independent experiments. (B, top panels) Absolute numbers (× 10⁴) of 6.5⁺CD25⁺ cells (closed symbols) and 6.5^–CD25⁺ cells (open symbols) within CD4SP thymocytes in TCR-HA transgenic mice 1 to 2 months after injection of a GFP-expressing (LvGFP) or HA-expressing (LvHA) lentiviral vector. (B, bottom panels) Absolute numbers (× 10⁴) of 6.5⁺CD25⁺ cells (closed symbols) and 6.5^–CD25⁺ cells (open symbols) within CD4SP thymocytes in TCR-HA or TCR-HAxIns-HA transgenic mice. Absolute numbers of cells were calculated by multiplying the total viable cell count, as determined by trypan blue exclusion, with the frequencies of cells in each population of interest. Each dot represents a value from individual mice in 2 separate experiments. The P values were calculated using unpaired t test.