NATURAL KILLER CELL ACTIVITY CORRELATES WITH AGE AND DIALYSIS DURATION IN HEMODIALYSIS PATIENTS

Abstract

Introduction and Aims: End-stage renal disease (ESRD) patients display an immunodeficiency state. Natural killer (NK) cells are lymphocytes of innate immune system that play a key role in an immune response towards viral infections and tumors. However, few studies have investigated NK cell functions in ESRD patients. Therefore, we aimed to analyze risk factors related to the NK cell activity in ESRD patients, especially hemodialysis (HD) patients.

Methods: Clinically 203 stable patients who were treated by HD for more than 3 months were enrolled from 4 outpatient HD clinics (male 102). NK cell activity was assessed using NK Vue™ assay (ATGen Co.) that uses serum of ex-vivo stimulated whole blood to detect interferon (IFN)-γ secreted from NK cells as an indicator of NK cell activity. All patients were stratified as abnormal (<250 pg/ml, n=63) and normal (≥250 pg/ml, n=140) groups according to NK cell activity.

Results: Mean age of the HD patients was 58.3±11.7 years (range 31 to 80 years) and mean HD duration was 62.1±50.8 months (range 3 to 310 months). Furthermore, 13.8% (n=28) and 17.2% (n=35) of HD patients showed abnormal (less than 100 pg/ml) and borderline (100-250 pg/ml) NK cell activity, respectively. In the abnormal NK cell activity group, age and WBC count were significantly higher as compared to the normal NK cell activity group (63.8±8.2 versus 57.9±12.3 years, p=0.009; 7347.8±2079.2 versus 6508.6±1894.7/uL, p=0.023). Dialysis duration in the abnormal NK cell activity group was 47.1±35.9 months, and shorter than that reported in the normal NK cell activity group (68.6±50.4 months, p=0.007). In multivariate regression analysis, old age (ß = 0.944, p = 0.005) and shorter dialysis duration (ß = 1.660, p = 0.040) were independent risk factors of abnormal NK cell activity in HD patients.

Conclusions: This study suggests age and dialysis duration are risk factors influencing NK cell activity in HD patients. The younger age patients and the patients with longer dialysis duration shows greater NK cell activity.