Early prediction of acute rejection after inbred rat kidney transplantation using macrophage migration inhibition test

In order to formulate an early diagnostic method for acute rejection after kidney transplantation, macrophage migration inhibition test (MIT) was carried out with lapse of time after inbred rat kidney allotransplantation. The mean survival time of rat kidney allograft was found to be 7.07 +/- 1.34 days. On the other hand, in the group treated with rabbit anti-rat lymphocyte serum (ALS) the mean survival time was lengthened to 14.15 +/- 2.14 days (p less than 0.05). The corresponding antigen used for MIT was prepared with donor kidney by ultrasonication, and its protein concentration at 180 mug/ml was the most optimal as not to elicit non-specific inhibition of macrophages. In the control group, activity of macrophage inhibitory factor (MIF activity) turned positive 3 days after the transplantation, and it became strongly positive by 5 or 7 dyas at the period when rejection crisis appeared frequently. ALS-treated group showed a lower MIF activity than the control group (p less than 0.05) and on 7-12 dyas before rejection crisis appeared frequently, MIF activity became strongly positive. These findings suggest that this MIT is simple and will be proved to be useful in predicting the acute rejection as well as in controlling the immunosuppression.