Interferon-gamma treatment increases HLA-DR expression on monocytes in severely injured patients.

Traumatic injury and sepsis reduce HLA-DR expression on monocytes. This study assessed the effect of interferon-gamma (IFN-gamma) on the expression of HLA-DR on monocytes taken from severely injured patients. The mononuclear layer of each blood sample was incubated with either 500 units IFN-gamma or control media. The mean baseline HLA-DR expression of the trauma group (n = 11) was 32%, significantly less than the mean HLA-DR expression of 91% for the control group (n = 10). In the trauma group, HLA-DR expression after culturing with IFN-gamma was 81%, significantly greater than both the mean baseline HLA-DR expression (32%). In the control group, HLA-DR expression after culturing with IFN-gamma was 94%, similar to the mean baseline HLA-DR expression of 91%. These data confirm that HLA-DR on monocytes of severely injured patients is markedly reduced and show that it can be increased significantly in vitro by IFN-gamma.