Background COPD is associated with chronic pulmonary and systemic inflammation. An imbalance between proinflammatory and antiinflammatory factors plays an important role in disease progression. T-Regulatory cells (Tregs) being the negative regulator of immune response have gained attention in many inflammatory diseases However, the functional role of Tregs in COPD is not clearly defined.

Aim To evaluate the relative percentage and suppressive functions of circulating T regulatory cells in COPD and controls

Methodology The study was conducted in 14 COPD patients (smokers n=7, reformed smokers n=7) and 14 age-matched healthy controls (smokers n=7, non-smokers n=7). PBMC were isolated and circulatory Tregs with phenotype CD4+CD25+CD45RA-CD127-FoxP3+ were identified by Flow Cytometry. The suppressive function of Tregs was evaluated by assessing the proliferation of T responder cells (CD4+CD25-) in the presence of circulatory Tregs (CD4+CD25+) under polyclonal stimulation.

Results FoxP3+ Tregs as a percentage of CD4+CD25+CD45RA-CD127-FoxP3+ were lower in COPD smokers as compared to control smokers ((60.1(66.7-56.4) vs. (90.4(91.9-78.4) p=0.04) and non-smokers ((60.1(66.7-56.4) vs. (95.5(96.7-89.8) p=0.0006). The percent suppression of T responder cells by Tregs was also lower in COPD smokers ((31.2(40.5-20.3) vs(63.4(82.8-53.0) p=0.03) and COPD reformed smokers ((25.65(37.7-24.2) vs. (63.4(82.8-53.0) p=0.04) as compared to control smokers.

Conclusion COPD is associated with a lower percentage and reduced suppressive capacity of T regulatory cells in peripheral circulation which may suggest their inability to suppress the persistent inflammatory response in COPD.