Compared with HCs, patients with IPF or pSS-IP did not have significant differences in the percentages of CD4+CD25++ cells (HCs: 7.22 ± 1.59%; IPF: 7.70 ± 2.68%; pSS-IP: 6.67 ± 1.31%; Fig. 1c). This evidence concerns the gene CD4 and incontinentia pigmenti.