Effects of propofol emulsion and thiopentone on T helper cell type-1/type-2 balance in vitro

We have earlier found increased percentages of T helper cells (CD4-positive lymphocytes) in the blood circulation after propofol infusion anaesthesia. Cytokines interferon-gamma (IFNgamma) and interleukin-4 (IL-4) are important in the differentiation of T helper cells into subtypes T helper type-1 (Th1) and type-2 (Th2). To study the effects of propofol emulsion, its solvent Intralipid(R) and thiopentone on Th1/Th2 balance, measurements of IFNgamma and IL-4 production by mononuclear leucocytes were carried out in vitro. As IL-2 has a central role in immune responses to surgery, its production was also measured. Concanavalin A-stimulated mononuclear cells were cultured in the presence of propofol emulsion at 3.5 or 10 mu g.ml(-1), Intralipid(R) 35 or 100 mu g.ml(-1), or thiopentone 3 mu g.ml(-1). Cytokine production was measured from the conditioned media of mononuclear cell cultures. Decreased IFNgamma (p < 0.001) and IL-4 concentrations (p < 0.01) were found in the presence of thiopentone, but IL-2 production was unaffected. By contrast, propofol emulsion or Intralipid(R) had no effects on IFNgamma, IL-2 or IL-4 concentrations. Propofol 10 mu g.ml(-1) increased the IFNgamma/IL-4 ratio from the control value median 243 (162-562) (25th-75th percentile) to 363 (195-1028) (p < 0.01), but thiopentone decreased it to 145 (60-214) (p < 0.01). These findings show that propofol and thiopentone have different effects in vitro on Th1/Th2 balance and suggest that they have different modulating effects on the immune response.