The e-cigarette vapour boosts the production of inflammatory chemicals and disables key protective cells in the lung that keep the air spaces clear of potentially harmful particles, revealed the study published online in the journal Thorax.
"In terms of cancer-causing molecules in cigarette smoke, as opposed to cigarette vapour, there are certainly reduced numbers of carcinogens", Professor Thickett said. "But if you vape for 20 or 30 years and this can cause COPD, then that's something we need to know about".
However the US Surgeon General has warned that e-cigarettes leave young people at risk of nicotine addiction, brain development problems and mood disorders, while the World Health Organisation has said it is concerned that heating e-fluid can lead to the 'formation of toxicants'.
Vaping or smoking e-cigarettes has been found to be a harmful practice.
Although e-cigarettes probably pose less of a cancer risk than regular cigarettes, whether they are as safe as manufacturers claim is unclear.
This is a "caution against the widely held opinion" that vaping can be used to aid in giving up cigarettes, the researcher said.
"Importantly, exposure of macrophages to [e-cigarette vapour condensate] induced numerous same cellular and functional changes in [alveolar macrophage] function seen in cigarette smokers and patients with COPD", they said.
Most research on the safety of vaping is based on the e-cigarette liquid before it's smoked.
The vaping process damaged the vital immune system cells, they concluded. The effects were even found to be similar to those found in cigarette smokers and lung disease patients. It believed that e-cigarettes can help one overcome the habit of smoking and should be allowed on prescription.
E-cigarettes don't proceed tar or carbon monoxide; two of the main toxins in cigarette smoke, said the NHS.
Public Health England, however, considers vaping safer than traditional cigarettes.
E-cigarettes are a relatively new phenomenon and thus not much has been known about them and the harm they can cause.
The US Surgeon General has however issued warnings that use of e-cigarettes among the young can lead to several problems such as nicotine addiction, mood swings and impairment of brain development. And inflammation is one of today's leading medical blame-carriers for all sorts of additional health woes, with this study suggesting it interferes with the alveolar macrophages in the lungs that pull out dust and infections.