PDCD1 and Huntington disease: Finally, CD274 expression on HD neutrophils was positively associated with erythrocytes (rho = 0.81, p = 0.008), while the expression of CD279 on these cells was negatively associated with circulating neutrophils (rho = −0.80, p = 0.01) and positively associated with blood lymphocytes (rho = 0.72, p = 0.03).