Posttraumatic expression of MHC II molecules: an experimental and clinical study.

OBJECTIVE: To evaluate the role of MHC II expression in posttrauma immune disturbances and infections. METHODS: In experimental study, peritoneal macrophages were harvested from traumatized mice and treated with GM-CSF, Ia molecules were determined by flow cytometry. In 24 trauma patients, monocyte HLA-DR expression was measured by APAAP technique. RESULTS: Marked inhibition of MHC II molecule expression was found in both traumatized mice and patients. In traumatic patients with infection, the inhibition was more severe. Treatment with GM-CSF in mice partially restored the Ia expression. CONCLUSIONS: Inhibition of MHC II molecules plays an important role in postrauma immune disturbances. There is a close relationship between HLA-DR inhibition and clinical infections.