Fig. 4

Knee osteoarthritis (KOA) synovial fluid (SF) monocytes/macrophages (MΦ) subsets and CD4+ T cells display an activated phenotype and correlate with each other. a Levels of HLA-DR expression in MΦs: mean fluorescence intensity (MFI) on peripheral blood mononuclear cell (PBMC) and SF MΦ subpopulations (SF leukocytes (SFLs), N = 40). b Frequency of activated cells in CD4⁺ T cells: CD69 + (early activation; N = 37), CD25+ (intermediate activation, SFLs, N = 37), HLA-DR+ (late activation, SFLs, N = 15). c Negative correlation between CD14⁺CD16⁺-MΦs (to total SF MΦs) ratio and the frequency of early activated (CD69⁺) CD4⁺ T cells; N = 82. d Negative correlation between CD14⁺CD16^neg-MΦs (to total SF MΦs) ratio and the frequency of late activated (HLA-DR⁺) CD4⁺ T cells; N = 32. a and b Median with interquartile range for box and Tukey-style whiskers. Lines between boxplots indicate significant differences with adjusted p value on top. White dots with white box represent data from PBMCs; black dots with gray box represent data from SFLs. c and d Pearson correlation coefficient (r) and adjusted p value shown