Another difference is that CD4+PD1+CXCR5+ Tfh cells within FL and CLL samples were completely depleted by the CXCR5 CAR-T cells whereas the CD19 CAR-T cells had no effect on Tfh cell numbers (Fig. 3i; Supplementary Fig. 8d, e). Here, CD4 is linked to B-cell chronic lymphocytic leukemia.