Current smoking status is associated with reduced sputum immunoglobulin M and G expression in COPD

The relationship between smoking status and total immunoglobulin levels in patients with COPD is not fully understood. Decreased immunoglobulin levels have been observed in patients with COPD [1–4], a disease largely attributed to current or former smoking, and cigarette smokers [5, 6]. These studies focused predominately on serum (systemic) or salivary (upper respiratory tract) immunoglobulins. Levels of immunoglobulins in induced sputum, a …