These mice showed an expansion of CD44highCXCR5+ PD-1high Tfh cells (Fig. 3 e–f) and CXCR5+ Bcl6+ Tfh cells (Fig. 3 g–h) in response to P. chabaudi infection, comparable to the levels detected in wt C57BL/6 control mice [we only detected a small, yet significant, reduction of the counts of CXCR5+ Bcl6+ cells in Sh2d1a−/− mice at day 8 post infection (Fig. 3H)]. Here, BCL6 is linked to infection.