IL17A and Parkinson disease: Furthermore, no statistical significance was found for other cytokines (IL-6, IL-10, IL-17) implicated in the involvement of T lymphocytes, which could indicate an activation of these cells in PD only later and a preponderant role of lymphocytes B. This might suggest an inflammatory pathogenesis of PD in response to an external stimulus (in genetically predisposed subjects), with a subsequent cascade activation of the immune system and damage to the dopaminergic circuits of the basal ganglia sensitive to this type of cellular response.