Upregulated intragraft gene expression, ICAM-1 and IL-2R molecules, and apoptotic epithelial cells during rejection of rat small intestine allografts

To investigate the kinetics and the magnitude of intragraft gene expression of interleukin-2 (IL-2), interferon-gamma (IFN-gamma), perforin and granzyme B, and intragraft expression of interleukin-2 receptor (IL-2R) and intercellular adhesion molecule-1 (ICAM-1) during acute rejection episodes, and to analyze the changes in apoptosis in small intestinal allograft rejection.Heterotopic small intestine transplantation was performed with inbred rats F344/N (RT1l) and Wistar/A (RT1-Ak, RT1-Ed). All recipients were divided into four groups: group 1: Wistar, native control; group 2: Wistar-->Wistar; group 3: F344-->Wistar and group 4: F344-->Wistar + cyclosporine A (6 mg.kg-1.d-1 i.m.). The grafts were harvested on postoperative days (PODs) 3, 5 and 7. All samples were examined pathologically. Intragraft mRNA expression of IL-2, IFN-gamma, perforin and granzyme B were detected with reverse transcriptase polymerase chain reaction (RT-PCR) and intragraft expression of IL-2R and ICAM-1 were stained using immunohistochemistry. We also analyzed the change in apoptosis rejection with terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL).Mild acute rejection occurred on POD 3 in the allograft group, moderate acute rejection on POD 5, and severe acute rejection on POD 7, while none of the isografts had histological evidence of acute rejection. Cyclosporine A could effectively control rejection. Gene expression was virtually negative in the native control. Only on POD 5 was IL-2 mRNA expression of allografts significantly higher than that of isografts (P < 0.05). IFN-gamma mRNA expression was significantly higher than that of the control groups (P < 0.01) on PODs 3, 5 and 7, and the level of perforin and granzyme B mRNA expression reached significantly higher levels than in the other two control groups on POD 5 and POD 7. Intragraft IL-2R expression of the allograft was significantly higher than that of the other three control groups. Only on POD 3 was intragraft ICAM-1 expression of allografts significantly higher than isografts. The number of apoptotic cells per crypt of allografts was significantly higher than that of the other three control groups on POD 3 and POD 5 (P < 0.01).Transcription of IL-2, IFN-gamma, perforin and granzyme B, and expression of IL-2R and ICAM-1 as well as apoptosis of epithelial cells of the grafts play an important role in small intestine allograft rejection. Intragraft gene expression of IFN-gamma and intragraft expression of IL-2R as well as apoptotic epithelial cells may become a specific and sensitive diagnostic method of clinical value. Furthermore, therapeutic strategies to alter these molecules in small intestine transplantation may improve the outcome of current antirejection therapy.