Figure 2 Alterations in cytotoxic lymphocyte subsets and perforin expression in patients with newly diagnosed secondary hemophagocytic lymphohistiocytosis (sHLH) and complete response sHLH (CR-sHLH). Proportions of circulating CD8+ T cells (TCRαβ+CD8+CD56−), natural killer (NK) cells (TCRαβ−CD56+), and CD56+ T cells (TCRαβ+CD56+) (A), and the percentage of perforin-positive cells within each respective lymphocyte subset (B) were compared between 19 newly diagnosed sHLH patients and 10 healthy controls. The proportion of NK cells was decreased, and the percentage of perforin-positive CD56+ T cells was elevated in sHLH patients, compared with healthy controls (P=0.006 and P=0.035, respectively). Lymphocyte subset proportions (C) and the percentage of perforin-positive cells within these subsets (D) were compared between 19 newly diagnosed sHLH patients and 6 CR-sHLH patients. The proportion of CD8+ T cells was significantly lower in CR-sHLH patients than in newly diagnosed sHLH patients (P=0.023). Data are presented as scatter plots with each point representing an individual patient; horizontal lines indicate the median and interquartile range. Statistical significance between independent groups was determined using the Mann-Whitney U test. Figure created with GraphPad Prism v8.0.