OBJECTIVETo study the real effect of IL-15, a kind of T lymphocyte activators which were derived from lymphocytes, on the acute rejection process in heart and liver transplantation in rats.

METHODSMale (body weight 200 - 250 g) 1A (RT1(a)) and LEW (RT1(l)) rats were selected as donors and recipients, respectively. Heterotopic heart transplantation (in abdomen) and orthotopic liver transplantation were performed as the acute rejection model group (experimental group); LEW (RT1(l))-->LEW (RT1(l)) as donors and recipients to establish isografts transplantation as the control group. Animals were sacrificed on day 1, 3, 5, 7 and graft specimens were collected. Microarray, immunohistochemistry and Western-blotting methods were used to detect the expressions of IL-15, IL-2 and IFN-gamma, etc. 48 rats were divided evenly into two groups and each time-point consisted of 6 rats.

RESULTSAcute rejections which were clarified by pathological findings and animal manifestations were found 3 days after operation in the experimental group. The early expression of IL-15 was found on endothelial cells in allografts 1 day after operation in contrast to IL-2, which expressed lately and only be found on inflammatory cells including lymphocytes and Kupffer cells 3 days after graft implantation. The result of INF-gamma was the same as that of IL-2.

CONCLUSIONSIL-15 appeared earlier in heart and liver allografts than IL-2 and IFN-gamma in rat acute rejection model, and the expression site differed from the later two. IL-15 participated in acute rejection reaction earlier in this process and the pathway may be different from IL-2 and IFN-gamma. Early blocking this pathway combined with other blockade would have a promising result in control of the progression of acute rejection.