Circulating CD4<sup>+</sup> T cells and Th1/Th2/Th17 subsets were quantified by flow cytometry, and soluble PrP<sup>C</sup> concentrations in plasma were measured by ELISA.<h4>Results</h4>Plasma soluble PrP<sup>C</sup> concentrations were higher in patients with ischemic stroke than in controls (1.16 [0.74, 1.99] ng/mL vs 0.54 [0.36, 0.65] ng/mL; P < 0.0001) and were further increased in the moderate-to-severe subgroup (1.91 [1.10, 3.18] ng/mL vs 0.86 [0.58, 1.40] ng/mL; P < 0.01). The gene discussed is PRNP; the disease is ischemic stroke.