CXCR3+, Th1-like TFH-cells, a subset lacking true ex vivo TFH function [34], were reduced in frequency in all subtypes of MS compared to HCs, and in PPMS there was an increased frequency of CCR6+, Th17-like TFH-cells (Figure 1E, F, G). Here, CXCR3 is linked to primary progressive multiple sclerosis.