CD4 and autoimmune thrombocytopenic purpura: We found a 2.3- and 2.7-fold increase of CD4+CXCR5+ TFHs and CD4+CXCR5+ PD1+ TFHs in ITP patients compared to healthy controls (3.88% [1.63-7.89] vs. 1.71% [0.49-2.78], P < 0.0001, Figure 2A; 2.47% [1.01-5.66] vs. 0.90% [0.31-1.97], P < 0.0001, Figure 2B).