Although the main source of IL-13 is generally thought to be CD4-positive Th2 cells, Fuschiotti et al. reported CD8-positive cells in the peripheral blood of SSc patients produced high levels of IL-13, which was more pronounced in dcSSc patients who develop extensive skin sclerosis compared with lcSSc patients, where skin sclerosis is limited [38]. The gene discussed is CD4; the disease is systemic sclerosis.