Changes in monocytic expression of aminopeptidase N/CD13 after major trauma.
HLA-DR expression on monocytes as marker for monocytic function is severely depressed after major trauma. The membrane enzyme aminopeptidase N/CD13 can trigger help in antigen processing by MHC class II molecules of antigen-presenting cells. We determined the simultaneous expression of HLA-DR and CD13 on peripheral blood monocytes of patients with major trauma (injury severity score of > or =16). 1 : 1 conjugates of phycoerythrin (PE)-to-monoclonal antibody were used in combination with QuantiBRITE PE beads for a standardized quantification in terms of antibodies bound per cell (ABC). The very low expression of HLA-DR antigen on monocytes of patients at day 1 after major trauma confirmed previous results in the literature. Monocytic HLA-DR expression increased slowly to reach values in the lower range of healthy volunteers at day 14. Monocytic CD13 expression at day 1 showed values in the range of healthy volunteers, and a strong rise afterwards. Fourteen days after trauma, the monocytic expression of CD13 was still much higher than in the control group. Because lipopolysaccharide (LPS) and the anti-inflammatory cytokine interleukin (IL)-10 have been shown to be involved in the depressed HLA-DR expression on monocytes in trauma patients, we studied the in vitro effects of LPS and interleukin (IL)-10 on the expression of CD13 on monocytes prepared from the peripheral blood of healthy volunteers. Whereas a 3-day IL-10 treatment resulted in a down-regulation of both HLA-DR and CD13 expression on monocytes, LPS caused a down-regulation of HLA-DR but a rapid up-regulation of CD13 levels. Therefore we suggest that, with respect to monocytic CD13 expression, LPS rather than IL-10 could well be the explanation for monocytic surface molecules after severe injury, although other mediators with a CD13 regulating function have to be considered.
Huschak
G
G
Department of Anaesthesiology, BG Kliniken Bergmannstrost, Halle, Germany.
Zur Nieden
K
K
Stuttmann
R
R
Riemann
D
D
D000328:Adult; D000368:Aged; D018826:CD13 Antigens / Q000032:analysis* / Q000276:immunology; D016022:Case-Control Studies; D002478:Cells, Cultured; D006259:Craniocerebral Trauma / Q000276:immunology; D003422:Critical Care; D005260:Female; D005434:Flow Cytometry; D006098:Granulocytes / Q000276:immunology; D006684:HLA-DR Antigens / Q000032:analysis*; D006801:Humans; D015601:Injury Severity Score; D016753:Interleukin-10 / Q000494:pharmacology; D007963:Leukocytes, Mononuclear / Q000187:drug effects / Q000276:immunology*; D008070:Lipopolysaccharides / Q000494:pharmacology; D008297:Male; D008875:Middle Aged; D009104:Multiple Trauma / Q000276:immunology*; D009504:Neutrophils / Q000276:immunology; D011446:Prospective Studies
D006684:HLA-DR Antigens; D008070:Lipopolysaccharides; D016753:Interleukin-10; D018826:CD13 Antigens