CXCL8 and Parkinson disease: Differential expression analysis identified one gene which was significantly down-regulated and eight genes which were significantly up-regulated in PD T cells (Fig. 3C; fc < / > 0.5, q < 0.05), with an enrichment of cytokines and chemokines (IL6, IL8, CXCL2, CXCL3, CXCL5).