Fig. 1

LRRK2 protein expression is significantly upregulated in monocytes from PD patients. a Spleen cells from LRRK2 KO and LRRK2 WT-OX mice were used to validate the suitable application of the rabbit-anti-LRRK2 antibody conjugated to AlexaFluor®647 from Novus Biologicals (NB300-268AF647) for intracellular flow cytometry analyses. The antibody showed a highly positive LRRK2 population in LRRK2 WT-OX cells (black histogram), whereas no LRRK2 staining was presented within KO cells (dark grey histogram), nor in LRRK2 WT-OX cells stained with the monoclonal rabbit isotype control (light grey histogram). The displayed experiment shows the fluorescence intensity of the different samples and is representative of three independent experiments. b Further validation experiments of intracellular LRRK2 staining for FACS analyses were performed with human whole blood samples. The human CD14⁺⁺ and CD16⁺ monocyte subpopulations showed positive staining for LRRK2 [anti-LRRK2 (Novus); orange histogram], while the isotype control staining did not show any nonspecific binding (‘IgG control’; dark grey histogram). The displayed graphs are representative of three independent experiments. c Leukocytes from whole blood samples of healthy controls (HC; n = 26) and PD patients (PD; n = 26) were analyzed by flow cytometry to detect LRRK2 protein in the different monocyte subsets. CD16⁺ monocytes (upper panel) as well as CD14⁺⁺ monocytes (lower panel) from PD patients displayed significantly higher LRRK2 expression compared to respective monocyte subsets from healthy controls. The histograms on the right are representative for the analyzed individuals and display the fluorescence intensity of the anti-LRRK2-AlexaFluor®647 antibody. The higher LRRK2 expression in monocytes of PD patients compared to healthy controls is demonstratively shown in these graphs. d Flow cytometric analyzes of CD19⁺ B-cells reveal no changes in the LRRK2 protein expression between healthy controls (n = 13) and PD patients (n = 17). The histograms on the right hand side represent the fluorescence intensity of the anti-LRRK2-AlexaFluor®647 antibody and show overlapping peaks which reveal no differences in LRRK2 expression. Error bars represent mean ± SEM; **p < 0.01; statistical significance was tested with non-parametric testing