Objective: To study the influence of sera from severely injured patients on the human leukocyte antigen (HLA)-DR expression of normal peripheral blood mononuclear cells (PBMC).
Design: In vitro study.
Setting: University hospital.
Patients and participants: Sera from 34 patients were obtained within 8 h after trauma. Seventeen of these patients developed posttraumatic sepsis (sepsis group) and 17 recovered without infectious complications. Sera from ten healthy individuals served as controls. Phytohemagglutinin (PHA)-activated PBMC from 44 healthy donors were used to study the effects of a patient's serum.
Measurements and results: Medium containing 5% of serum from the sepsis group significantly ( p<0.05) reduced the HLA-DR expression (channels, mean +/- standard error of the mean) on monocytes (patients 883+/-22, controls 962+/-15), B (patients 922+/-14, controls 972+/-7) and T cells (patients 932+/-13, controls 968+/-5) of PHA-activated PBMC. Significantly increased accumulation of TNFalpha on (1.8+/-0.4% of PBMC) and within T cells (0.98+/-0.26% of PBMC) was observed by flow cytometry after incubation with medium containing sera of the sepsis group compared with controls (on 0.5+/-0.1%, within 0.27+/-0.05% of PBMC). A significant negative correlation between relative cell counts of intracellular TNFalpha-positive T cells with HLA-DR expression was observed for monocytes ( r= -0.61), B cells ( r= -0.57) and proliferation ( r= -0.68) as estimated by (3)H-thymidine uptake [patients 139971+/-12844 counts per minute (cpm), controls 198973+/-19347 cpm, p<0.05] in the presence of sera from the sepsis group.
Conclusions: Reduced cellular immunity and, therefore, immunodeficiency after trauma appears to be caused by soluble factors influencing T cell function in particular.