Extended Data Fig. 7: The Group 3 TCR SKV does not facilitate thymic Treg cell development at low clonal frequencies.

The Group 3 SKV TCR was cloned and expressed as low-frequency TCRrg mixed bone marrow chimeras (see Methods). TCRrg T cells were directly phenotyped using flow cytometry. Thymocytes were gated on CD73^neg cells to distinguish newly developed thymocytes from recirculating mature T cells in the thymus⁵⁹. a, Representative flow cytometric analysis of thymic (top, CD73^negTCRβ⁺Thy1.1⁺) and splenic (bottom, TCRβ⁺CD4⁺Thy1.1⁺) TCRrg T cell frequency recovered from low-frequency TCRrg mixed bone marrow chimeras. b, Representative flow cytometric analysis of Foxp3 vs. CD4 expression by thymic CD4SP (top, CD73^neg TCRβ^hiCD4⁺CD8β^negThy1.1⁺) and splenic CD4⁺ (bottom, TCRβ⁺CD4⁺Thy1.1⁺) TCRrg T cells from low-frequency TCRrg mixed bone marrow chimeras. Far right column, thymic CD4SP (CD73^negTCRβ^hiCD4⁺CD8β^neg) and splenic CD4⁺ (TCRβ⁺CD4⁺) T cells from untreated B6.SJL mice served as positive controls. c, Representative flow cytometric analysis of Foxp3 vs. CD69 (top) and Ki67 (bottom) expression by splenic CD4⁺ (TCRβ⁺CD4⁺Thy1.1⁺) TCRrg T cells from low-frequency TCRrg mixed bone marrow chimeras. Far right column, splenic CD4⁺ (TCRβ⁺CD4⁺) T cells from untreated B6.SJL mice served as controls. Data is representative of at least two independent experiments. Representative flow plots are ordered from highest (left) to lowest (right) thymic TCRrg frequency.