Effect of synthetic colloids on major histocompatibility complex class II expression

Study ObjectiveSynthetic colloids are used for perioperative fluid management. We hypothesized that their use may be associated with changes in major histocompatibility complex (MHC) class II expression. This could affect patients' morbidity and mortality during clinical intervention.SettingUniversity research laboratory.SubjectsWhole blood samples from healthy volunteers.InterventionsWhole blood samples from healthy volunteers (n = 6) were incubated with different concentrations of hydroxyethyl starch (HES) from maize and potato (pHES), dextran, and polygelin (gelatine) for 24 hours with or without 100 U/mL human interferon γ (IFN-γ; stimulus for MHC class II expression). The expression of human leukocyte antigen (HLA): HLA-DR, HLA-DQ, and HLA-DP was detected simultaneously by a fluoresceinisothiocyanate (FITC)-labeled antibody and analyzed by flow cytometry on lymphocytes and monocytes.Measurements and Main ResultsHydroxyethyl starch, pHES, and dextran induced a significant increase in HLA expression. The induction of MHC class II was independent of the structure (50 mg/mL: control, 8.7±1.4%; HES, 28 ± 9.7%; pHES, 29.8 ± 11.7%; and dextran, 50.2 ± 8.1%). In contrast, polygelin increased HLA expression only at the highest concentration of gelatine (5 mg/mL, 7.8 ± 1%; 50 mg/mL, 7.6 ± 0.8%; 100 mg/mL, 7.3 ± 1%; 200 mg/mL,16.2 ± 2.3%). The addition of IFN-γ decreased HLA expression in presence of highest concentration of HES and dextran.ConclusionIn an ex vivo laboratory setting, we demonstrate that high concentrations of plasma expanders are associated with increased HLA expression on lymphocytes and monocytes. However, further in vivo studies are necessary to demonstrate the clinical significance of this observation.