Figure 5. Elevated Nfkbid expression increases suppressive capacity of Tregs that are at least partially responsible for T1D resistance in NOD-60A mice.

(A) The capacity of CD4⁺CD25⁺ Tregs expressing varied levels of Nfkbid (standard NOD, NOD-Nfkbid^−/− and NOD-60A, n=4 for each strain) to suppress T-cell proliferation was measured in cultures containing 5×10⁴ CD4⁺CD25⁻ NOD responder T-cells labeled with cell proliferation dye, 2.5×10⁵ APC from NOD.scid mice and 20μg/ml CD-3 antibody. (B) At four days after sublethal irradiation (600 cGy) splenic Treg levels were 99% decreased in both NOD and NOD-60A mice compared to non-irradiated strain-matched controls (data not shown) but remained higher in the latter strain (n=13 for both strains). (C) Rag1^null.AI4 CD8 T-cells transfer T1D at a significantly higher level to NOD control than 60A mice, and Treg depletion by i.p. injection with 62.5μg of the CD25 specific PC61 Ab partially abrogates disease protection in the latter strain. T1D developmental comparisons were analyzed by log-rank (Mantel-Cox) test. (D) Treg levels in Panc LNs at 14 days following sub-lethal irradiation in AI4 T-cell infused NOD (n=12) or NOD-60A mice that did (n=15) or did not (n=11) also receive a single anti-CD25 antibody injection. For A, B and D, statistical comparisons determined by Mann-Whitney nonparametric comparison.