Regulatory T-cell phenotype is associated with ex vivo response to BsAbs. Shown is a representative contour plot of regulatory T cells, which were identified as viable CD3⁺CD4⁺FoxP3⁺CD25^+/− cells of the total CD4⁺ T cells. Shown are 42 (A) or 33 biologically independent (B-C) samples. Box plots in panel C of the indicated markers show either the median fluorescence intensity (MFI) or the frequency of positive (+) cells of total FoxP3⁺CD25^+/− T cells. Differences between both response groups or between B-NHL and reactive lymph node (rLN) samples were evaluated by using the two-sided Wilcoxon’s test. P values were corrected for multiple testing by using the Benjamini-Hochberg procedure. (D) Additional markers were determined in 15 biologically independent samples and correlated among each other. Spearman’s correlation coefficients (R) are displayed if the absolute R value was ≥0.4. (E) Forest plot illustrating a multivariate logistic regression with the indicated covariates and response status (responder, nonresponder) as dependent variable. The model was calculated separately for FoxP3⁺CD25^+/− regulatory T cells. ***≙ P ≤ .001; *≙ P ≤ .05; missing asterisks indicate P > .05.