DISTINCT METHYLATION OF THE INTERFERON-GAMMA (IFN-GAMMA) AND INTERLEUKIN-3 (IL-3) GENES IN NEWLY ACTIVATED PRIMARY CD8(-LYMPHOCYTES - REGIONAL IFN-GAMMA PROMOTER DEMETHYLATION AND MESSENGER-RNA EXPRESSION ARE HERITABLE IN CD44(HIGH)CD8(+) T-CELLS() T)

Differential genomic DNA methylation has the potential to influence th e development of T cell. cytokine production profiles. Therefore, we h ave conducted a clonal analysis of interferon (IFN)-gamma and interleu kin (IL)-3 gene methylation and messenger (m)RNA expression in primary CD8(+) T cells during the early stages of activation, growth, and cyt okine expression. Despite similar distributions and densities of CpG m ethylation sites, the IFN-gamma and IL-3 promoters exhibited different ial demethylation in the same T cell clone, and heterogeneity between clones. Methylation patterns and mRNA levels were correlated for both genes, but demethylation of the IFN-gamma promoter was widespread acro ss >300 basepairs in clones expressing high levels of IFN-gamma mRNA, whereas demethylation of the IL-3 promoter was confined to specific Cp G sites in the same clones. Conversely, the majority of clones ex-pres sing low or undetectable levels of IFN-gamma mRNA exhibited symmetrica l methylation of four to six of the IFN-gamma promoter CpG sites. Geno mic DNA methylation also has the potential to influence the maintenanc e or stability of T cell cytokine production profiles. Therefore, we a lso tested the heritability of IFN-gamma gene methylation and mRNA exp ression in families of clones derived from resting CD44(low)CD8(+) T c ells or from previously activated CD44(high)CD8(+) T cells. The patter ns of IFN-gamma gene demethylation and mRNA expression were faithfully inherited in all clones derived from CD44(high) cells, but variable i n clones derived from CD44(low) cells. Overall, these findings suggest that differential genomic DNA methylation, including differences amon g cytokine genes, among individual T cells, and among T cells with dif ferent activation histones, is an important feature of cytokine gene e xpression in primary T cells.