Impact of e-cigarette vaping on the immune system across the body

Although electronic cigarettes (e-cigarettes) have only been intensely studied since 2016, we have learned that the chemicals contained within e-cigarette aerosols (commonly called vapor) directly impact the function and phenotype of immune cells across the body (see Graphical Abstract). This review focuses on white blood cells (leukocytes) as well as immune functions of epithelial cells, which are critical for host defense. We also detail the modulation of inflammatory mediators in different compartments, such as saliva, blood, and airways, by e-cigarette vaping. Data are summarized across in vivo animal models, in vitro and ex vivo exposures of human and mouse cells, and human subjects, with an emphasis on human data. A multitude of changes in immune cells and inflammatory mediators in response to e-cigarette vapor exposure have been identified, and here we synthesize what is known and the likely effects on physiology across the body.