Unregulated APC activation by T cells breaks self-tolerance

The absence of nTregs results in slight increase of B7 on dendritic cells (DC). Such slightly elevated B7 induce proliferation of T cells with intrinic high self-affinity: bidirectional T/DC interaction ensues, leading to progressive DC activation and reciprocal strong T cell activation. mRNA were purified from lymph node or spleen dendritic cells of germ-free Rag KO mice adoptively transferred with FACS-purifed naïve CD4 T cells or Tregs before a week.