Ozone exposure stimulated natural killer cells in a laboratory study

Background: natural killer cells and the immune system

Natural killer (NK) cells are white blood cells of the innate immune system. They recognise and destroy virus-infected cells and abnormal cells, including some tumour cells, without needing prior exposure to a specific target. Because medical ozone is used as a complementary therapy and is thought to influence oxidative balance and immune signalling, researchers have asked whether ozone exposure changes how human immune cells behave. At the time of this study, its direct effects on human NK cells had not been well characterised.

Study design: ozone-exposed blood cells from healthy donors

This was an in vitro (laboratory) study. The researchers isolated peripheral blood mononuclear cells - a mix of immune cells that includes NK cells - from healthy human donors. The cells were exposed to low doses of ozone (1 and 5 micrograms per millilitre). Using flow cytometry, the team measured cell viability, cell proliferation, the proportion of NK cells present, and NK cell cytotoxic activity, indicated by expression of the degranulation marker CD107a.

Findings: more NK cells and greater cytotoxic activity in the dish

The study reported that low-dose ozone exposure did not reduce the viability of the cells or impair their ability to proliferate. Compared with untreated cells, ozone exposure was associated with a higher proportion of NK cells among the mononuclear cells and with increased NK cell cytotoxic activity, reflected in raised CD107a expression. These changes were observed in cultured cells rather than in people.

What the authors concluded

The authors concluded that transient ozone exposure appears to have influential effects on human NK cells, consistent with a possible immunomodulatory role for medical ozone. They were careful to frame this as a preliminary laboratory observation and noted that further research is needed to clarify the underlying mechanisms and whether the effect has any bearing on immune function in the body.

Limitations of this study

This was a small in vitro study using cells from healthy volunteers, so its findings describe what happened to isolated cells in the laboratory, not what happens inside a living person. It did not measure any clinical outcomes, follow participants over time, or test whether ozone therapy given to patients produces the same changes or any health benefit. The doses and conditions used in a dish do not necessarily correspond to those in clinical practice. This study concerns the behaviour of immune cells exposed to ozone in the laboratory. It does not examine ozone as a treatment for cancer itself. Ozone therapy is a complementary approach and should always be discussed with your oncology team.