Williams-Gray CH, et al. - Experts gauged whether age-related changes in the immune system (immunosenescence) are of particular relevance in Parkinson’s disease (PD), as its prevalence rises with increasing age. They investigated this with respect to T cell replicative senescence, a key immune component of human ageing. Findings for the first time suggested that, for an older population, the peripheral immune profile in PD was distinctly atypical, with a lack of the CD8+ T cell replicative senescence that characterizes normal ageing, suggesting the contribution of “abnormal” immune ageing to the development of PD.