Figure 3 Representative flow cytometry plots illustrating altered lymphocyte profiles in secondary hemophagocytic lymphohistiocytosis (sHLH). Flow cytometry data from 1 representative sHLH patient and 1 healthy control (HC) are shown. Panels (A, B) compare the gating for CD8+ T cells (TCRαβ+CD8+CD56−), natural killer (NK) cells (TCRαβ−CD56+), and CD56+ T cells (TCRαβ+CD56+), showing a markedly reduced NK-cell proportion in the sHLH patient, compared with the HC. Panels (C, D) compare intracellular perforin staining within the CD8+ T cells, NK cells, and CD56+ T cells, showing that the percentage of perforin-expressing cells in CD56+ T cells is visibly higher in the sHLH patient than in the HC. Gates for perforin positivity were set using isotype controls (red peak). Figure created with Kaluza v2.0.