Increased Neopterin Concentration in Older Age Coincides with Decline of CD28 + CD45RA + T-cells

Neopterin is produced from human monocyte-derived macrophages and dendritic cells upon stimulation with interferon-γ, and increased neopterin concentrations thus indicate cell-mediated immune activation. In healthy individuals increasing neopterin concentrations are found with increasing age, which is also evident from the age- dependency of reference values of serum neopterin concentrations. Increase of neopterin concentrations in the el- derly may relate to, e.g., altered T lymphocyte differentiation with age. In this study, serum neopterin concentra- tions of 138 persons (median age: 34 years; interquartile range 29.0 - 67.8 years) were investigated and compared to age and to the percentage of CD28 + CD45RA + or CD28 + CD45RO + subsets among CD8 + T cells. With increa- sing age, the percentage of CD28 + CD45RA + in CD8 + T-cells decreased (Spearman's rank correlation coefficient: rs = -0.561; p < 0.0001) accompanied by an increase of the percentage of CD28 + CD45RO + in CD8 + T-cells (rs = +0.221; p < 0.01). Serum neopterin concentrations increased with age (rs = +0.541; p < 0.0001). This increase of neopterin concentration was accompanied by a decreased percentage of CD28