Since PTX3 maintains homeostatic equilibrium in the local immune responses and dysregulation of lung homeostasis can contribute to the pathogenesis of pulmonary emphysema, we examined the mean linear intercept (Lm), a measure of alveolar space enlargement, in WT and Ptx3 KO mice (N = 8 animals/group). The gene discussed is PTX3; the disease is pulmonary emphysema.