IL-15 gene expression is associated with improved clinical outcome in patients with B-cell lymphomas. (A) Scatter plot of excess deaths (martingale residuals of the survival outcome in an empty Cox model) vs IL-15 gene expression (log2); tertile categories are separated by vertical dashed lines: low (<4.9), intermediate (4.9-5.9), high (>5.9). A loess curve with 95% confidence bands (gray) is indicated. (B) Kaplan-Meier plot for overall survival of patients categorized according to tertiles of IL-15 expression. (C) Correlation between IL-15 and Granzyme B (GZMB) or (D) Perforin 1 (PRF1) mRNA levels visualized using scatter plots and fitted linear model estimates with 95% confidence bands. R_s, Spearman rank correlation coefficient.