In group comparative analyses (PAH, ILD, uncomplicated systemic sclerosis (named SSc no PAH no ILD), and controls), CD3 and CD56 were higher in PAH patients, with respect to the controls, ILD, and the group SSc no PAH no ILD (CD3: p = 0.01, p = 0.003, p = 0.0005; CD56: p = 0.002, p < 0.0001, p = 0.0002). This evidence concerns the gene NCAM1 and systemic sclerosis.