Type 2 cytokines from iNKT cells regulate thymic egress. (A) CD45/IL-13GFP in thymus cells from IL-13GFP mice. (Right) PBS57/TCRβ in CD45⁺IL-13GFP⁺ cells. (B) Quantitative PCR of DP, SP4, and thymic PBS57⁺ iNKT cells. Error bars indicate SEM. (C) WT thymocytes stimulated with PMA/Ionomycin. (Left) Gating on iNKT cells. (Right) IL-4/IL-13 production by iNKT cells. (D) Thymus sections of WT and CD1d^−/− mice, and quantitation of conventional SP4 in grafts. Bars, 100 μm. (A–D) Data typical of at least three experiments, and six mice of each strain. (E) Thymic-resident iNKT cells identified in transplants as CD45.1⁺CD45.2⁻ cells. iNKT cell frequency in thymic-resident cells is shown with IL-4/IL-13 production after stimulation. Data represent four experiments; n = 18. Error bars indicate SEM. A Mann-Whitney nonparametric U test was performed. **, P < 0.01.