Subpopulations of IELps generate TCRαβ⁺ CD8αα IELs with differential efficiency. (A and B) Congenically marked PD-1⁺α₄β₇⁺CD103⁻ (CD45.1/2⁺) and PD-1⁻α₄β₇⁻CD103⁺ (CD45.1⁺) CD122⁺ IELps (CD4^−/dullCD8^−/dullNK1.1⁻TCRβ⁺CD5⁺CD122⁺; A) or congenically marked PD-1⁺α₄β₇⁺CD103⁻ (CD45.1/2⁺) and PD-1⁺α₄β₇⁻CD103⁻ (CD45.1⁺) CD122⁺ IELps (B) were sorted and adoptively transferred into RAG1-deficient animals at a 1:1 ratio. Small intestines were harvested from recipient mice 6 wk later and analyzed for the presence of IEL populations. CD45.1 and CD45.2 expression profiles of total IEL cells from recipient mice (left). TCRβ⁺CD4⁻ cells were gated on within each Donor⁺ population and were analyzed for expression of CD8β and CD8α (middle). Frequencies of CD8αα, CD8αβ, and CD8⁻ cells within TCRβ⁺CD4⁻ from the indicated donor derived populations (right). For A, data were collected from n = 5 recipient mice over four individual experiments. For B, data were collected from n = 5 recipient mice over three individual experiments. Error bars indicate SEM.