IMMUNOLOGICAL MARKERS IN A LONGITUDINAL-STUDY OF AGING IN PIGTAILED MACAQUES (MACACA-NEMESTRINA)

Blood lymphocyte subsets, serum immunoglobulins (Ig), response of lymphocytes to mitogens, and natural killer (NK) cell activity were evaluated as potential biomarkers for primate aging. All were evaluated in a cross-sectional study of 60 pigtailed macaques (Macaca nemestrina) ranging from 2 to 32 years of age. Lymphocyte responses to mitogens were lower in older animals than in most younger ones. NK cell activity showed no clear relation to age cohort. In a longitudinal study of lymphocyte subsets and immunoglobulins, class I restricted T cells (CD8(+bri)) of the memory (CD18(+bri)) subtype increased with age, whereas those of the naive (CD18(+dull)) subtype decreased with age in females. A class II restricted T-cell subset (CD4(+)CD45RA(-)), which includes memory T cells, increased with age in females. Serum IgA increased. These results support the utility of memory and naive subsets of CD8(+) T cells, CD4(+) T cells, and serum IgA as biomarkers for longitudinal studies. Total lymphocytes, total T cells, CD4(+) T cells, and CD8(+) T cells may also be useful in this species.