Relationship between TH1/TH2 cytokines and immune tolerance in liver transplantation in rats.

OBJECTIVE: To explore the relationship between Th1/Th2 cytokine expressions and immune tolerance in rat liver transplantation.

METHODS: Recipients were divided into three groups (each group = 12 rats). The allograft group underwent orthotopic liver transplantation from male Wistar-to-Sprague-Dawley (SD) rats. The isograft group of SD-to-SD liver transplantation was complemented with a control group of normal male SD rats that had sham operations. We evaluated the 2-week survival rates histological changes, as well as serum and mRNA expression levels of Th1/Th2 cytokines: interferon-gamma (IFN-gamma) and interleukin-10 (IL-10).

RESULTS: The 1-week survival in the isograft and allograft groups were 100% and 41.67%, respectively. The 2-week survival rates were 75% and 8.33% (P < .05). Light microscopic inspection revealed severe acute rejection in the allograft but not the isograft group in the first week postoperation. This observation was verified by the cellular morphology under transmission electron microscopy. Serum IFN-gamma (Th1 cytokine) levels (pg/mL) determined by enzyme-linked immunosorbent assay in the allograft, isograft, and control groups were 386.67 +/- 14.36, 159.83 +/- 16.53, and 87.83 +/- 8.67, respectively; for IL-10 (Th2 cytokine), they were 126.33 +/- 13.10, 288.33 +/- 17.10, and 70.50 +/- 7.23, respectively (P < .05, allograft vs isograft). The semiquantitative reverse-transcriptase polymerase chain reaction assay showed that expression of IFN-gamma and IL-10 mRNA was similar to that of serum levels. IFN-gamma mRNA was more highly expressed in the allograft group and IL-10 mRNA, in the isograft group (P < .05).

CONCLUSIONS: The dynamic equilibrium of Th1/Th2 cytokines is critically involved in immune tolerance. The deviation of Th1 to Th2 may be one mechanism of immune tolerance.