HLA-DR expression and soluble HLA-DR levels in septic patients after trauma

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 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.