However, when we investigated Tang cell subsets on the basis of the expression of CD4, CD8 and CD28 antigens, we could not find any significant difference in the proportions of CD4+, CD8+, CD28+ and CD28null Tang cells either between SSc patients and HC or between SSc patient subgroups stratified according to the severity of peripheral vasculopathy. This evidence concerns the gene CD28 and systemic sclerosis.