Low B and T lymphocyte attenuator expression on CD4(+) T cells in the early stage of sepsis is associated with the severity and mortality of septic patients: a prospective cohort study

INTRODUCTION: B and T lymphocyte attenuator (BTLA) is an inhibitory receptor, whose primary role in CD4(+) T cell is thought to inhibit cytokine production. We explore BTLA expression on CD4(+) T cells in healthy controls and septic patients, and assess the correlation of BTLA expression on CD4(+) T cells in the early stage of sepsis with the severity and mortality of septic patients in the emergency department (ED). METHODS: 336 consecutive patients were included in this study. BTLA expression on CD4(+) T cells was measured by flow cytometry within 24h of ED admission. RESULTS: Our results showed that the percentage of BTLA(+)/CD4(+) T cells was high expression in healthy volunteers and it was statistically reduced in severe sepsis and septic shock compared with healthy controls(all P<0.01). The area under the receiver operating characteristic (AUC) curves of BTLA expression on CD4(+) T cells was slightly lower than that of procalcitonin (PCT) and Mortality in Emergency Department Sepsis (MEDS) score. The percentage of BTLA(+)/CD4(+)T cells was lower in non-survivors than in survivors (P<0.01), and similar results were obtained when expressed as mean of fluorescence intensities (MFI) (P<0.01). Adjusted logistic regression analysis suggested that the percentage of BTLA(+)/CD4(+) T cells was associated with 28-day mortality in septic patients (odds ratio (OR) = 0.394). CONCLUSION: Our study shows that the percentage of BTLA(+)/CD4(+) T cells was high in healthy volunteers. Furthermore, lower percentage of BTLA(+)/CD4(+) T cells during the early stage of sepsis is associated with the severity and the mortality of septic patients.