OBJECTIVE

To investigate the expression of non-T cell derived cytokines in acute rejection after heart transplantation.

METHODS

The hearts of 26 C57BL/6 mice were transplanted into the abdominal cavities of 26 Balb/c mice (acute rejection group). The hearts of 26 Balb/c mice were transplanted into the abdominal cavities of another 26 Balb/c mice (syngeneic control group). After the operation, heart beat was felt with finger at the abdomen every day to determine the survival of the transplanted heart. One, three, five, and seven days after the operation the transplanted hearts were taken out from 5 mice in each group respectively to undergo microscopy. RT-PCR was used to detect the mRNA expression of these cytokines: interleukin (IL)-2, IL-15, tumor necrosis factor (TNF)-alpha, and interferon (IFN)-gamma. Western blotting was used to detect the protein expression of these cytokines. Six mice in each group, totally 12, were used to observe the survival time of transplanted heart.

RESULTS

The mice of the control group recovered more rapidly in comparison with the nice of the acute rejection group. The survival times of the transplanted hearts of the control group were all longer than 100 days, significantly longer than those of the acute rejection group (7-9 days, P < 0.01). No sign of acute rejection was found in the hearts of the control group, and significant lymphocyte infiltration was seen in the myocardium of the acute rejection group 3-7 days after the operation. In the control group, no mRNA expression of IL-2 and IFN-was seen at any time-point, and IL-15 mRNA and TNF-alpha mRNA were expressed at low level at any time-point. However, in the acute rejection group the mRNA expression of IL-2, TNF-alpha, and IL-15 could be detected since the first day post-operatively and peaked on the day 5, but the mRNA expression of IFN-gamma could be detected and peaked only on the 5 th post-operative day. The mRNA expression levels of these 4 cytokines at any time point of the acute rejection group were all significantly higher than those of the control group (P < 0.01 or P < 0.05). The proteins of the 4 cytokines were all expressed at low level at any time point in the control group. However, in the acute rejection group the protein expression levels of IL-15 and IL-2 began to increase since the third day after operation and the protein expression levels of TNF-alpha and IFN-gamma began to increase since the first day after operation.

CONCLUSION

Many cytokines, including T cell derived and non-T cell derived cytokines, are involved in the pathogenesis of acute rejection after allogeneic organ transplantation.