Apoptosis of peripheral blood lymphocytes in patients with LRRK2-associated Parkinson’s disease

Mutations in the Leucine Reach Repeat Kinase 2 (LRRK2) gene are the most frequent cause of familial Parkinson’s disease (PD). Although the precise physiological and pathological roles of LRRK2 are unclear, a direct link between mutant LRRK2 and programmed cell death (apoptosis) has been suggested. By using flow cytometry (PI+Annexin V(FITC)), we showed an increased level of spontaneous lymphocyte apoptosis in patients with LRRK2-associated PD compared to controls after 24 h (p < 0.016) and 48 h (p < 0.031) of incubation (5% CO2, 37°C). We found an increased FAS mRNA level in peripheral blood lymphocytes of patients with LRRK2-associated PD compared to controls (p < 0.05) and to sporadic PD (sPD) (p < 0.002). A significant difference in FAS expression between patients with LRRK2-associated PD and controls remained after 3 years and was detected after 1 and 24 h during lymphocyte incubation (p < 0.03 and 0.05, respectively). Increased spontaneous lymphocyte apoptosis, along with increased FAS expression, in patients with LRRK2-associated PD suggests that LRRK2 mutations may lead to preferable activation of extrinsic apoptotic way.