Objective: To determine if cellular and soluble HLA-DR molecules may be relevant in severely injured patients for the development of gram-positive or gram-negative sepsis.
Summary background data: HLA-DR molecules play a central role in the specific immune response to infection. The reduced HLA-DR expression on monocytes is considered to correlate with infectious complications and the development of sepsis. Data on the role of HLA-DR expression on T cells and soluble HLA-DR molecules are rare.
Methods: HLA-DR expression on monocytes and T cells was measured by flow cytometry. Plasma levels of soluble HLA-DR were studied by enzyme-linked immunosorbent assay.
Results: HLA-DR expression on circulating T cells, calculated as mean fluorescence intensity in channels, was reduced at day 1 after admission in 20 patients with subsequent severe sepsis compared with 46 patients without sepsis. The septic patients immediately after trauma had significantly lower soluble HLA-DR plasma levels than the nonseptic patients. At day 2 after admission, HLA-DR expression on monocytes was significantly lower in the severe sepsis group than in the patients without sepsis, and lasted until day 14 after injury.
Conclusions: In severely injured patients, decreased levels of cellular and soluble HLA-DR appear as early indicators of an immune deviation associated with the development of severe sepsis. Moreover, immune alterations of different cell types may promote distinct kinds of septicemia.