CD27 and glioblastoma: Taking a closer look at the Bc clusters, higher percentages of CD19+CD20− double negative (CD27−IgD−; DN) Bc (Bc 2), CD21− DN memory Bc (Bc 21), and Pc (Bc 23) were found in glioblastoma patients compared to controls, whereas the fraction of CD24+/CD27+ regulatory Bc (Bregs) (Bc19) and (CD5+) activated transitional Bc (TZB) (Bc 5 & Bc 11) were reduced (Fig. 5B-G).