Is low monocyte HLA-DR expression helpful to predict outcome in severe sepsis?

Abstract

Low monocyte human leukocyte antigen-DR (HLA-DR) expression has been reported to be an indicator of poor survival in critically ill septic patients. We assessed its usefulness as a prognostic indicator in order to identify possible interventions to normalise HLA-DR expression in those patients with lowered monocyte HLA-DR. HLA-DR expression was measured on separated monocytes of septic patients, using flow cytometry, and HLA-DR upregulation was measured by the same techniques after ex vivo stimulation with granulocyte macrophage colony stimulating factor (GM-CSF). APACHE II score, age, sex and outcome were determined for all patients. A single-centre study at the Royal Liverpool University Hospital in a medico-surgical 13-bed intensive care unit. All septic patients ( n=70) fulfilling the criteria of the ACCP for the diagnosis of sepsis were recruited for the study with informed consent from day 1 of diagnosis of sepsis and monocyte HLA-DR expression measured on 3 consecutive days. Patients were excluded from the study if they were on immunosuppressive therapy. Normal healthy volunteers ( n=45) were included. Low monocyte surface expression and median fluorescence density HLA-DR expression was not associated with a high mortality. High APACHE II scores were not correlated with low HLA-DR expression. However, in those patients where HLA-DR expression was lowered, this could be restored ex vivo by GM-CSF. In the group of septic patients under study, HLA-DR was not a useful prognostic marker of outcome. We did not find a higher mortality in the group of patients who had low expression. These findings are contradictory to some previously reported findings, and the possible reasons are discussed.