NCAM1 and Parkinson disease: Interestingly, when DRD3 expression was compared in HC and PD patients, we did not find differences in DRD3 expression in total CD4+ T-cells (CD3+ CD4+), naive CD4+ T-cells (CD3+ CD45RA+ CD4+), memory/effector CD4+ T-cells (CD3+ CD45RO+ CD4+), B-cells (CD19+) and NK cells (CD56+) upon resting conditions (Figure 1A, left panel).