CD8A and pulmonary arterial hypertension: In their study, Edwards et al. included patients with IPAH and connective tissue disease-associated PAH (CTD-PAH) and correlated lymphocyte profiles with survival rate within the first 3 years, revealing that low levels of NK cells and CD8+ T-lymphocytes were associated with increased risk of death, particularly in patients with CTD-PAH (Table 1).