Ageing is associated with a decline in peripheral blood CD56^brightNK cells

• Main Authors: Nayak Laxman, Chan Y L Tracey, Khan Naeem, Chidrawar Shivani M, Moss Paul AH
• Format: Article
• Language: English
• Published: BMC 2006-11-01
• Series: Immunity & Ageing
• Online Access: http://www.immunityageing.com/content/3/1/10

<p>Abstract</p> <p>Background</p> <p>Natural killer (NK) cells are cytotoxic lymphocytes that lack CD3 and express variable levels of CD16, CD56 and CD57. In recent years NK cells have been categorised into two major groups based on the level of CD56 expression. This phenotypic classification correlates with functional activity as CD56^brightNK cells are the major cytokine producing subset whereas CD56^dimNK cells exhibit greater cytotoxic activity. Previous studies have revealed a reduction in total NK cell numbers in association with ageing and this study sought to determine the potential influence of ageing on the number of NK cell subsets within peripheral blood.</p> <p>Results</p> <p>The number of NK (CD56⁺CD3^-) cells within peripheral blood did not change with increasing age. The number of CD56^dimNK cells also remained stable with ageing. In contrast the absolute number of CD56^brightNK cells within peripheral blood declined by 48% with ageing from a mean of 15.6/μl in individuals aged 20–40 years to 8.1/μl in those aged 60+ years (<it>p = 0.0004</it>).</p> <p>Conclusion</p> <p>The number of CD56^brightNK cells within peripheral blood declines with age. As this population plays a central role in cytokine secretion during the innate immune response this decline may contribute to impaired immune regulation in elderly individuals</p>