CD27 and Huntington disease: The frequency of activated memory (CD19+CD27+CD21−) B cells and plasmablasts/antibody-secreting cells (ASC) (CD19+CD38+CD27+) peaked on day 20 (24.1 and 34.3%, respectively) and was markedly higher than that in HD (2.6% [2.1–3.8] and 0.32% [0.25–0.75], respectively), as was that of exhausted CD19+CD27−CD21low/neg B cells (21.5% versus 2.1% [1.2–4.4] in HD) (Fig. 2e).