GENETIC-CONTROL OF THE DECLINE OF NATURAL-KILLER-CELL ACTIVITY IN AGING MICE

Mt cell activity declines with age and is strain dependent. We investi gated the age associated decline of NK cell activity in the HW26C stra in of mice. The bilineal congenic strain HW26C which contains a segmen t of chromosome 4 of BALB/cBy introduced onto the C57BL/6By (B6) backg round was used to investigate the decline of NK cell activity with age . Our experiments showed that there is a significant decline of NK cel l activity in old (18-26 months) HW26C mice as compared to the B6. By contrast, the NK cell frequency determined using a surface marker for NK cells, NK1.1, did not show any significant difference with age. It appears therefore, that the decline in NK activity during aging is a r eflection of loss of lytic activity rather than an actual decline in t he number of NK cells and the responsible gene(s) resides in chromosom e 4.