Level of NK cytotoxic activity in the elderly aged more than 80 years

A group of healthy volunteers aged 60-93 years, was evaluated with respect to their NK activity. These people have been under careful medical observation for 3 years and were selected according to Senieur Protocol criteria. NK activity of each person was checked at least three times at regular 12-month intervals with the chromium release test and twice at the same interval of time with a single cell cytotoxicity assay. NK activity of 60-79-year-old females was in a similar range of values as that of young females (20-35 years) and was lower than that of the males of the corresponding age groups. The females aged 80-88 years revealed the highest NK activity. The chronically ill 80-88-year-old females, on the other hand, were characterized by a marked decrease of NK activity in relation to their age counterparts. NK activity of both the females and males significantly declined at the age of 89-93 years. The significance of NK activity for survival is discussed.