Researchers at Life Center Chaum, a healthcare facility under CHA Network, and Bundang CHA Hospital have published a study on the natural killer (NK) cell activity in recurrent respiratory disease patients.

NK cells are immune cells that represent the body's primary defense action. The cells can recognize and kill abnormal cells or cancer cells and thus are important to maintain immunity.

The research team, led by Professors Lee Yoon-kyung at Chaum and Kim Young-sang at Bundang CHA Hospital, analyzed and compared 311 patients who received polyvalent mechanical bacterial lysate (PMBL) therapy, which prevents and treats respiratory diseases by normalizing immunity from 2016 to 2020, and 549 control subjects who had no recurrent respiratory diseases.

The average level of NK cell activity before treatment in recurrent respiratory patients was 463 picograms (pg) per millilambert (mL), less than half of the NK cell activity level of the control group's average of 962 pg/mL.

After PMBL therapy in recurrent respiratory patients, NK cell activity increased by 287 pg/mL.

Notably, in the low NK cell activity group (500 pg/mL or less), the NK cell activity increased significantly with an average increase of 384 pg/mL, confirming that PMBL therapy is effective in enhancing immunity in patients with recurrent respiratory infections.

"We confirmed that patients with respiratory infections had low NK cell activity, which required them to receive immune testing and management," Professor Lee said. "If patients show frequent signs of cough, sputum, or rhinitis, they need to take the right medication and exercise to improve immunity even in everyday life."

In a situation where research on the importance of increasing NK cell activity is lacking, Lee added that this study showed the possibility of immunotherapy in various diseases.

Journal of Clinical Medicine published the result of the study.