Aim: After an initial septic hit, the immune response to a new antigen changes as time progresses, with an unpredictable efficiency. The aim of this study was to characterize the monocyte functional phenotype by HLA-DR expression in septic patients at the onset of sepsis and during recovery in relation to organ failure and plasma mediators.
Methods: Twenty-six patients were analyzed as either single organ failure at worst (SOF) or multiple organ failure (MOF) over 14 days. Twelve patients received immunosuppressive (IS) drugs before sepsis. We measured: 1) monocyte HLA-DR expression (mHLA-DR); 2) plasma pro-inflammatory mediators (IL-12p40, macrophage Migration Inhibitory Factor [MIF]); 3) plasma anti-inflammatory mediators (IL-10, cortisol); and 4) in vitro lipopolysaccharide (LPS) stimulated mHLA-DR in 6-hour whole blood culture or after plasma replacement with standard milieu.
Results: mHLA-DR expression was equally decreased in patients who were treated with IS drugs as those who were not. Despite the difference in severity, SOF patients showed a similar profound mHLA-DR downregulation as MOF patients at day 0, but tended to recover earlier. MOF patients presented higher plasma IL-10 and cortisol levels than SOF patients but similar plasma IL-12p40 and MIF levels. In vitro LPS stimulation showed an impaired mHLA-DR response in both groups. Plasma replacement by milieu elicited a slight improvement in the response to LPS in SOF but not MOF patients.
Conclusions: At the onset of sepsis, an initial low mHLA-DR was not related to any prior IS drug regimen, the severity of the sepsis or the outcome. The duration of mHLA-DR downregulation could be related to plasma factors in SOF, while other mechanisms may be implicated in MOF evolution.