We observed that the MFI of BTLA on CD4+ T cells was significantly higher in patients with SIRS or sepsis than in healthy controls (P <0.01), but there was no statistically significant difference between the MFI of BTLA on CD4+ T cells in patients with severe sepsis or septic shock and healthy controls (all P >0.05). This evidence concerns the gene CD4 and systemic inflammatory response syndrome.