Association of γδ T cells with disease severity and mortality in septic patients

Abstract

Gamma-delta T cells are the most abundant of all epithelial-resident lymphocytes and are considered a first line of defense against pathogens in the mucosa. Our objective was to confirm the reduction in γδ T cell subsets and its relationship with mortality in patients with sepsis. We studied 135 patients with sepsis attended in the emergency department and intensive care unit of two hospitals and compared them with a similar control group of healthy subjects. The αβ and γδ T cell subsets were determined via flow cytometry according to the stage of the sepsis and its relationship with mortality. All the lymphocyte subsets were reduced with respect to the corresponding subsets in the control group. All the γδ T cell populations decreased significantly as the septic picture worsened. Furthermore, γδ T cells showed decreases at days 2, 3, and 4 from the start of sepsis. Twenty-six patients with sepsis died (19.3%). The γδ T cells, specifically, the CD3(+) CD56(+) γδ T cells, were significantly reduced in those septic patients who died. Our results indicate that, during sepsis, γδ T cells show the largest decrease and this reduction becomes more intense when the septic process becomes more severe. Mortality was associated with a significant decrease in γδ T cells.

Fig 1

Peripheral blood T cell subsets, both conventional and according to the αβ and γδ receptors, in relation to the stages of sepsis. Values are expressed as means (×10⁹/liter), and I bars denote 95% confidence intervals. Significant differences between the control group and patients in the 3 stages of sepsis (P < 0.001) were determined. The numbers of patients in each group were as follows: sepsis, n = 48; severe sepsis, n = 59; and septic shock n = 28.

Fig 2

Peripheral blood T cell subsets according to the αβ and γδ receptors in relation to time since onset of infection/sepsis at admission in ED/ICU departments. The numbers of patients in each group were as follows: 1 day, n = 48; 2 days, n = 32; 3 days, n = 22; and four or more days, n = 33. Values are expressed as means (×10⁹/liter), and I bars denote 95% confidence intervals.

Fig 3

Peripheral blood T cell subsets according to the αβ and γδ receptors in relation to mortality (n = 26) after hospital admission for sepsis. Values are expressed as means (×10⁹/liter), and I bars denote 95% confidence intervals.