Naïve CD4+ T cells are highly plastic and can differentiate into discrete lineages with unique
functions during an immune response. Once differentiated, helper T cells maintain a stable
transcriptional memory of their initial lineage choice and resist redifferentiation. During
embryogenesis, de novo DNA methylation operates on the hypomethylated genome of the
blastocyst to achieve tissue-specific patterns of gene expression. Similarly, the ifnγ promoter
is hypomethylated in naïve T cells, but Th2, Th17, and iTreg differentiation is accompanied …