Age Related Natural Killer Activity of Peripheral Blood Lymphocytes from Healthy Subjects and Cancer Patients. A Comparative in Vitro Study with Interleukin-2

Impact of Smoking on Human Natural Killer Cell Activity: A Large Cohort Study

Some studies have reported a decrease in the natural killer (NK) cell activity in smokers. However, large-scale data on the relationship between NK cell activity and smoking are unavailable. A cross-sectional study was performed on 12,249 asymptomatic examinees who underwent an NK cell activity test, between January 2016 and May 2017. The test quantitated the amount of interferon-γ secreted into the plasma by NK cells, using a patented stimulatory cytokine. The mean age of the study population was 39.1 years, and the proportions of “never”, “former”, and “current” smokers were 65.5%, 20.9%, and 13.6%, respectively. Current smokers (1,422 pg/mL) had a lower median level of NK cell activity than never smokers (1,504 pg/mL, P = 0.039) and former smokers (1,791 pg/mL, P < 0.001). Among current smokers, NK cell activity decreased with increase in the number of cigarettes smoked among current smokers (median, 1,537, 1,429, and 1,175 pg/mL at <10, 10-19, and ≥ 20 pack-years, respectively; P < 0.001). Additionally, it decreased linearly with increasing quartiles of cotinine levels (median, 1,707, 1,636, 1,348, and 1,292 pg/mL at cotinine levels < 292, 292-879, 880-1,509, and ≥ 1,510 ng/mL, respectively; r = –0.122, P < 0.001). NK cell activity was lower in current smokers. It also decreased with an increase in the number of cigarettes smoked, and it was negatively correlated with cotinine levels among current smokers. Our findings indicate a clear relationship between smoking and decreased NK cell activity.

Psychosocial stress moderates the relationship of cancer history with natural killer cell activity

Data suggest that both cancer history and psychosocial stress may be associated with reductions in natural killer cell activity (NKA). Therefore, we tested whether individual differences in cancer history, chronic/perceived stress, and their interactions would be associated with decreased levels of NKA. We tested these hypotheses in 80 spouse caregivers of victims of Alzheimer's Disease (AD) (persons known to report high levels of psychosocial stress) and in 85 age- and sex-matched spouses of non-demented controls. Participants were assessed at study entry (Time 1) and 15-18 months later (Time 2). Individuals with cancer histories (N = 43) had not been treated with immune altering medications within the last year. At both Times 1 and 2, cross-sectional main effects were weak or absent for cancer history, perceived stress (e.g. high hassles, low uplifts), and caregiver status; however, interactions occurred between cancer history and perceived stress, such that persons with cancer histories and high hassles/low uplifts had the lowest NKA values (p < .05). These results occurred even after controlling for age, gender, beta-blocker use, hormone replacement therapy, alcohol, and exercise. At Time 1, an interaction also occurred between caregiver status and cancer history--caregivers with cancer histories had lower NKA than did controls with cancer histories and caregivers/controls without cancer histories (p < .05). At Time 2, this interaction only showed a trend (p < .08), primarily because caregivers with cancer histories experienced increases in NKA (p < .05) from Time 1 to Time 2, whereas in the other three groups NKA did not change. Importantly, in caregivers with cancer histories, high perceived stress at Time 1 predicted low NKA at Time 2 (p < .05). This research suggests that the combinations of biological vulnerabilities and chronic/perceived stress may have interactive effects resulting in reduced NKA.

Prolactin response of NK cells, but not of LAK cells, is deficient in patients with carcinoma of oral cavity and during aging

The regulatory role of prolactin (Prl) on peripheral blood natural killer (NK) and lymphokine-activated killer (LAK) cell activities was studied in young (mean age, 40 years) and elderly (mean age, 68 years) healthy men and patients with carcinoma of the oral cavity (oral cancer). The peripheral blood NK cells, but not the LAK cells, were found to be depressed in oral cancer patients compared with age-matched healthy men. However, age-associated deficiency in both NK and LAK cell activity was observed in healthy men and cancer patients. Prl produced dose-dependent inhibition (1, 10, 100 or 250 ng/ml) or stimulation (25-50 ng/ml) of resting NK cells in young groups of healthy men and cancer patients. In elderly groups less or no response of the NK cells to low doses of Prl (1-10 ng/ml) was evident. The NK cells of young and elderly healthy men were stimulated by human recombinant Interleukin-2 (rIL-2) (100 U/ml), and Prl (1-25O ng/ml) inhibited these cells. In oral cancer patients an altered response to low doses of Prl (1-5O ng/ ml) was observed in IL-2-stimulated NK cells, which also revealed malignancy- associated loss of IL-2 response. In contrast, there was no malignancy or age-associated change in Prl response of the LAK cells. Treatment of peripheral blood lymphocytes of both healthy men and oral cancer patients for 5 days with Prl (50 ng/ml) in the ++presence of low concentration of serum generated LAK cells.

Natural killer (NK) and lymphokine-activated killer (LAK) activities in a patient who recovered from cancer, and the characteristics of LAK cells generated from CD4-CD8- and CD8+ peripheral blood lymphocytes

The natural killer (NK) and lymphokine-activated killer (LAK) activities of a patient who recovered from bladder transitional cell carcinoma were determined. The patient was diagnosed in 1980 and repeated several therapies until 1986. Since 1987, he has been in a tumor-free state. Recently, very high NK and LAK activities were found. The NK activity was recognized not only against the NK-sensitive cell line K562, but also against NK-unsensitive Raji and Daudi cell lines and against autotumor cell line H41. The percentage of CD16+ in peripheral blood lymphocytes (PBL) was 52.9%, the CD8+CD16+ was 26.3%, and the CD4-CD8-CD16+ was 26.6% (17.5, 5.4 and 12.1% in healthy blood donor (control), respectively). Because the patient had large numbers of CD4-CD8- cells in the PBL, CD4-CD8- LAK were generated from them. The CD4-CD8- LAK cells exhibited extremely high killer activity, whereas the CD8+ LAK cells generated from the CD8+ cells showed a low level of killer activity. These results suggest that the tumor-free condition of this patient may be related to these high killer activities. In this patient, several cytokines were also determined, although the results were not completely interpreted.