To build the optimal EBV-HLH risk prediction model, we conducted LASSO regression analysis of these variables, with twelve variables selected through cross-validation: ferritin, CD3+CD8+ T cell ratio (%), the ratio of CD4+ and CD8+T cells (CD4+/CD8+), CD3-CD16+CD56+ T cell ratio (%), HBDH, EBV-DNA copy number, anti-EBV-VCA-IgM, anti-EBV-VCA-IgG, anti-EBV-NA-IgG, IL-6, IL-10 and IFN-γ (Figure 1). Here, CD8A is linked to hemophagocytic syndrome.