To determine the cellular source of elevated IL-36γ within the airways of COPD subjects, gene expression of IL-36 cytokines was examined in key cells involved in COPD pathogenesis: lung tissue-derived macrophages (TMφ), small airway fibroblasts (SAF), and small airway epithelial cells (SAEC). The gene discussed is IL36G; the disease is chronic obstructive pulmonary disease.