IL10 and chronic obstructive pulmonary disease: Previous research has shown decreased IL-10 levels and increased IL-6/IL-10 ratio’s in bronchial secretions and serum of COPD [25, 26] but since many inflammatory cells (monocytes, macrophages, mast cells, and T-& B-lymphocytes) can produce IL-10 [27], we can now attribute the observed decrease in IL-10 to decreased production by B-reg cells.