Concomitant Assessment of Monocyte HLA-DR Expression and Ex Vivo TNF-α Release as Markers of Adverse Outcome after Various Injuries—Insights from the REALISM Study

Abstract

Intensive care unit (ICU) patients develop an altered host immune response after severe injuries. This response may evolve towards a state of persistent immunosuppression that is associated with adverse clinical outcomes. The expression of human leukocyte antigen DR on circulating monocytes (mHLA-DR) and ex vivo release of tumor necrosis factor α (TNF-α) by lipopolysaccharide-stimulated whole blood are two related biomarkers offered to characterize this phenomenon. The purpose of this study was to concomitantly evaluate the association between mHLA-DR and TNF-α release and adverse clinical outcome (i.e., death or secondary infection) after severe trauma, sepsis or surgery in a cohort of 353 ICU patients. mHLA-DR and TNF-α release was similarly and significantly reduced in patients whatever the type of injury. Persistent decreases in both markers at days 5–7 (post-admission) were significantly associated with adverse outcomes. Overall, mHLA-DR (measured by flow cytometry) appears to be a more robust and standardized parameter. Each marker can be used individually as a surrogate of immunosuppression, depending on center facilities. Combining these two parameters could be of interest to identify the most immunosuppressed patients presenting with a high risk of worsening. This last aspect deserves further exploration.

Utility of monocyte HLA-DR and rationale for therapeutic GM-CSF in sepsis immunoparalysis

“…Pros and cons of mHLA-DR expression, TNF-α secretion, and ALC as prognostic indicators in sepsis IP are summarized in Table 2 ( 4 , 26 , 27 , 30 , 35 , 130 , 138 , 139 ). mHLA-DR expression and TNF-α responsiveness seek to measure similar biology of innate immune MNP dysfunction ( 26 , 27 , 130 ).…”

“…Nonetheless, testing for this biomarker requires flow cytometry of fresh or stabilized cells, necessitating either shipping to a central facility or timely local analysis ( 74 , 140 ). By contrast, TNF-α secretion requires local site addition of LPS to blood samples and incubation followed by analysis of frozen cell supernatants by enzyme-linked immunosorbent assay (ELISA) ( 138 ). This procedure generates need for trained site staff to perform ex-vivo LPS stimulation reliably.…”

Prospective flow cytometry analysis of leucocyte subsets in critically ill patients who develop sepsis: a pilot study

“…Elevated levels of these suppressor cells have frequently been reported in sepsis patients, re ecting severity of disease and predisposition to secondary infections, but very seldomly in injury, such as in our study, prior to the occurrence of a primary infection [50][51][52]. The second recent large multicenter study explored mHLA-DR and ex vivo TNF-α release in sepsis, trauma and postoperative patients in association with adverse clinical outcome (death or secondary infection) [19,28]. It showed persistent decreases of both markers at days 5-7 post ICU admission to be associated with both outcomes, whatever the type of injury.…”

“…The most commonly studied parameter of immune dysfunction associated with injury is the low HLA-DR expression on monocytes (mHLA-DR), which induces an impaired functional state of these cells. The latter feature has been associated with secondary sepsis and sometimes outcome in severe trauma, burn and postoperative patients [15][16][17][18][19][20][21].Targeted treatment has been tempted in that context. Older studies have shown contrasted clinical outcomes after immunotherapy, based on GM-CSF or IFNγ administration, despite e cacious restoration of mHLA-DR and/or IFNγ endogenous secretion [22][23][24].…”

“…By contrast, higher SOFA score, admission for brain injury and lack of prophylactic antibiotics were predominant in patients who developed sepsis. Moreover, septic patients displayed higher hospital and ICU length-of-stay compared to non-septic patients (26 days [16-71] versus 11 days [9-16], p < 0.0001 and 15 days[10][11][12][13][14][15][16][17][18][19][20][21][22] versus 3 days[2][3][4], p < 0.0001, respectively). Septic patients also displayed a higher 28-day and 90-day mortality compared to non-septic patients (36.8% versus 7.5%, p = 0.0028 and 38.9% versus 8.9%, p = 0.0038, respectively).…”