Deficit of interleukin 7 in septic patients

•Serum levels of cytokine 7 at admission were lower in septic patients.•γδ T cell frequency decreased with the time and severity of sepsis.•IL-7 levels remained stable over time and were independent of sepsis severity.•Mortality was related with low frequency of γδ T cells and normal levels of IL-7.•In patients who died IL-7 levels positively correlated with CD8 + γδ T cells.

We recently demonstrated an overall decrease of all αβ and specially γδ T cell subsets in patients with sepsis compared with healthy subjects. IL-7 is a crucial factor for development of γδ T cells and survival in sepsis but its association with sepsis severity, evolution of organ failure and death still has not been investigated. Sera from 78 patients who met criteria for sepsis were analyzed vs control group. Septic patients showed the lowest levels of IL-7. Patients with severe sepsis reached levels of IL-7 higher than those observed in the groups of uncomplicated sepsis and septic shock. The frequency of γδ T cells at admission was lower in septic patients vs control group. At the time of admission, the frequency of γδ T cells in septic patients who subsequently died was lower than the observed in the group of patients that instead survived.