Alterations of T cell subsets in ALS: a systemic immune activation?

There is evidence that immunological factors may involved in pathogenetic mechanisms of amyotrophic lateral sclerosis (ALS). Few studies to date have explored the status of the systemic immune response in patients with ALS.In order to examine whether systemic immune activation is observed in patients with ALS, we measured the number of T cell subsets by flow cytometry in 36 patients with ALS and 35 normal controls.CD8 cytotoxic T cells and natural killer (NK) T cells were significantly increased in our patients with ALS compared with the control group (P = 0.02 and P = 0.04, respectively). Treg cells were significantly reduced compared with normal controls (P = 0.01). Treg cells were also negatively correlated with progression of the disease (P = 0.017).Our results suggest a systemic immune activation in patients with ALS. The high production of CD8(+) T and NKT cells may suggest an immunological reaction to some unknown or undetected endogenous proteins or viruses. A probably dual (neurodestructive or neuroprotective) inflammatory function of Treg cells cannot be excluded.