Abstract
SummaryAge-related changes in immunity are well documented in humans and laboratory mammals. Using blood samples collected from wild Soay sheep, we show that pronounced differences in T-cell subsets and inflammatory markers amongst age classes are also evident under natural conditions. These shifts parallel those observed in mammals experiencing protected environments. We found progressive declines in the proportion of naïve CD4 T cells with age, a precipitous drop in γδ T cells after the second year of life and an increase in acute phase protein levels amongst geriatric sheep. Our findings suggest immune aging patterns observed in laboratory and domestic mammals may generalize to more complex, challenging environments and could have fitness costs under natural conditions.
Highlights
The proportion of T helper cells (CD4+) increased from around 25% of the total circulating lymphocyte population in lambs to 35% in geriatric sheep (F3,43 = 9.63, P < 0.001; Fig. 1A)
The proportion of naıve helper T cells (CD4+ CD45RA+) declined progressively amongst age classes from around 35% to < 10% (F3,42 = 57.97, P < 0.001; Fig. 1B)
We found that two acute phase proteins, haptoglobin and serum amyloid A, were higher on average in geriatric sheep than in yearlings and adults (F3,42 = 5.22 and F3,40 = 2.93, respectively, both P < 0.05; Fig. 2A,B)
Summary
Citation for published version: Nussey, DH, Watt, K, Pilkington, JG, Zamoyska, R & McNeilly, TN 2012, 'Age-related variation in immunity in a wild mammal population', Aging Cell, vol 11, no.
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