Human leukocyte antigen-DR expression in peripheral blood mononuclear cells from healthy donors influenced by the sera of injured patients prone to severe sepsis

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 TNF 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 TNF-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 ³H-thymidine uptake [patients 139,971±12,844 counts per minute (cpm), controls 198,973±19,347 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.