Differential methylation of the proximal IL-1α promoter region in predominantly allele-specific–expressing CD4⁺T-cell clones. DNA from T-cell clone 41 (A), 90 (B), and 36 (C) was treated with bisulfite, and the promoter region and intron IV were amplified by PCR and cloned. Of each region, multiple clones were sequenced. Each circle represents a CpG. In this and all subsequent figures, filled black circles represent a methylated CpG, white circles represent an unmethylated CpG, and gray circles represent a CpG that could not be analyzed in the sequence. Eight CpGs were analyzed in the 5′ regulatory region (–7 through +1). Thirteen CpGs were analyzed (+17 through +29) in intron IV.