CD4 and multiple sclerosis: Our results showing that duplication of the IL2RA locus potentiates CD25 expression and IL-2 signaling are reminiscent of previous reports showing that CD25 surface expression on memory T cells is variable and can be correlated with haplotypes of the IL2RA region, conferring susceptibility to type I diabetes and multiple sclerosis.33 Along the same line, susceptibility to UC and CD associates with single nucleotide polymorphisms (SNPs) in the IL2RA locus3 although quantitation of CD25 surface expression on CD4+ T cells of individuals bearing this IBD-associated SNP has not yet been reported.