Tumor necrosis factor in graft rejection. In situ hybridization study

The development of necrosis and macrophage infiltration increases the risk of renal graft rejection. But the macrophages secrete the alpha form of the tumour necrosing factor (TNF) which is also involved in several immunologic and inflammatory phenomena. We therefore studied the expression of the gene TNF alpha by in situ hybridization during advanced stage rejection after renal transplantation: the grafts were infiltrated with macrophage-like cells expressing the mRNA of the TNF alpha gene, particularly deep in the cortex and in the medulla. These cells then secrete the TNF alpha molecule since they are recognized by anti-TNF alpha antibodies. These antibodies also recognize certain other glomerular endothelial and tubular epithelial cells which do not express the TNF alpha gene: these cells are undoubtedly the TNF target cells. These findings confirm the synthesis of TNF alpha in advanced stage renal graft rejection.