Natural killer (NK) cells are the bodyguards of our immune system and are considered our first line of defense.
Their job is to destroy invading pathogens, foreign bodies, and infected cells in early stages, thereby preventing them from spreading hence decrease in a number of NK cells can lead to immune system dysfunction and increase susceptibility to disease.
Anxiety disorder and insomnia are two conditions that can disrupt the normal functioning of the immune system.
Given these disorders are quite common, researchers in Saudi Arabia have now examined the association between anxiety, insomnia, and NK cells in young, female students and then published their results in Frontiers in Immunology.
60 female students, aged between 17 and 23 years old, participated in the study and filled out three questionnaires about sociodemographics as well as anxiety and insomnia symptoms.
The symptoms of the latter two were self-reported and showed that around 53% of the participants reported sleeping disturbance suggestive of insomnia, and 75% reported anxiety symptoms.
Participants also provided blood samples through which percentages of NK cells and their subtypes were determined.
NK cells have two subtypes: the first type, CD16+CD56dim cells make up the majority of NK cells in the nervous system that connects the central nervous system to the rest of the body.
Cells belonging to this subtype also exhibit cytotoxicity (cell toxicity), which means they can damage or kills cells that invade the body.
The other subtype, CD16+CD56high cells, are less frequent and involved in the production of proteins that function as chemical messengers and in immunoregulation (regulation of the immune system).
The results of the study showed that students with anxiety symptoms had a lower number of circulatory NK cells and their sub-populations, compared to students who did not report symptoms.
Severity of symptoms also played a role as students as participants with moderate and severe anxiety symptoms had a significant lower percentage of circulatory NK cells compared to students without them.
Among students with minimal or mild anxiety symptoms, only a statistically insignificant decline in NK cell percentage was observed. While in students with insomnia symptoms, higher anxiety scores were negatively associated with the proportion of total peripheral NK cells.
