Fig. 4. ICOS expression in memory T cells correlates with Tph cell and plasmablast B-cell frequency in rheumatoid arthritis patients.

Mass cytometry data were analyzed from PBMCs of 18 healthy control and 27 RA patients. A Frequency of memory cells in CD4⁺ T cells and (B) ICOS+ cells among memory CD4 + T cells in 45 donors. C–E Correlation between frequency of ICOS⁺ cells among memory T cells and frequency of Tph among memory T cells, Tfh among memory T cells, or plasmablasts among B cells. Flow cytometry using PBMCs from blood of 8 healthy controls (blue) and synovial fluid of 9 RA patients (red) were examined for ICOS expression and Tph cells proportion. F Frequency of memory cells in CD4⁺ T cells and G Tph cells in memory T cells in 17 donors. H From synovial fluid of RA patients, correlation between the frequency of ICOS among memory T cells and the frequency of subsets including Tph cells among memory T cells. Error bars are mean $\pm$ S.D. P values from Mann-Whitney two-tailed U-test (F, G). Pearson correlation with a two-tailed test (C–E, H).