0041-1337/98/6611-1465$03.00/0 TRANSPLANTATION Vol. 66, 1465–1471, No. 11, December 15, 1998 Copyright © 1998 by Lippincott Williams & Wilkins Printed in U.S.A. MACROPHAGE MIGRATION INHIBITORY FACTOR EXPRESSION IN HUMAN RENAL ALLOGRAFT REJECTION 1,2 HUI Y. LAN, 3,4 NIANSHENG YANG, 3 FIONA G. BROWN, 3 NICOLE M. ISBEL, 3 DAVID J. NIKOLIC-PATERSON, 3 WEI MU, 3 CHRISTINE N. METZ, 5 MICHAEL BACHER, 5 ROBERT C. ATKINS, 3 AND RICHARD BUCALA 5 Department of Nephrology, Monash Medical Centre, Clayton, Victoria 3168, Australia, and Picower Institute for Medical Research, Manhasset, New York 11030 Background. Macrophage migration inhibitory fac- tor (MIF) plays a pivotal role in immune-mediated dis- eases. Despite the long-standing association of MIF with the delayed-type hypersensitivity response, the potential role of MIF in allograft rejection is unknown. Methods. MIF expression was assessed by in situ hy- bridization and immunohistochemistry staining in 62 biopsies of human renal allograft rejection and in nor- mal human kidney. Results. MIF mRNA and protein is constitutively ex- pressed in normal kidney, being largely restricted to tubular epithelial cells, some glomerular epithelial cells, and vascular smooth muscle cells. In both acute and chronic renal allograft rejection, there was marked up-regulation of MIF mRNA and protein ex- pression by intrinsic kidney cells such as tubular epi- thelial cells and vascular endothelial and smooth mus- cle cells. There was also MIF expression by infiltrating macrophages and T cells. Of note, macrophage and T cell infiltrates were largely restricted to areas with marked up-regulation of MIF expression, potentially contributing to the development of severe tubulitis and intimal or transmural arteritis. Quantitative anal- ysis found that increased MIF expression in allograft rejection gave a highly significant correlation with macrophage and T cell accumulation in both the glo- merulus and interstitium (P<0.001). In addition, the number of MIF1 tubules and interstitial MIF1 cells correlated significantly with the severity of allograft rejection (P<0.01), and the loss of renal function (P<0.01). In contrast, no up-regulation of renal MIF expression and no leukocyte accumulation was seen in allograft biopsies without evidence of rejection. Conclusions. This is the first study to demonstrate that local MIF expression is up-regulated during allo- graft rejection. The association between up-regulation of MIF expression, macrophage and T cell infiltration and the severity of renal allograft rejection suggests that MIF may be an important mediator in the process of allograft rejection. Allograft rejection is characterized by graft infiltration by T cells and macrophages (1–3). T cells can cause graft dam- age both directly through cytotoxic mechanisms and indi- rectly through cytokine release and by the recruitment and activation of macrophages in a delayed-type hypersensitivity (DTH*) response (4, 5). Indeed, recent studies have demon- strated that macrophage infiltration correlates inversely with renal graft function and is the single best predictor of renal graft survival (3, 6–8). On this basis, it is postulated that the cytokine macrophage migration inhibitory factor (MIF) plays a pivotal role in the process of allograft rejection. MIF was originally described as a product of activated T cells that inhibited the random migration of guinea pig peri- toneal macrophages in vitro and promoted macrophage accu- mulation in the DTH reaction (9, 10). However, despite the long-standing association of MIF with the DTH reaction, it is only recently that the functional role of MIF in the immune and inflammatory responses has been determined. In vivo blocking studies have shown that MIF plays a pivotal role in the tuberculin-induced skin DTH reaction (11), experimental models of arthritis (12), endotoxic shock (13, 14), and can act as a counter-regulator of glucocorticoid action (15). MIF has also been shown to play an important role in primary anti- genic and mitogenic stimulation of T cell activation and T cell-dependent antibody production (16). Furthermore, renal MIF expression is up-regulated in association with macro- phage infiltration in experimental models of immunologic kidney disease (17–19). Administration of a blocking anti- MIF antibody in a rat model of crescentic glomerulonephritis caused a significant inhibition of renal T cell and macrophage infiltration and activation, preventing a loss of renal function (20). These findings point towards MIF being an important player in the process of allograft rejection, although this remains to be proven. Therefore, the aim of the current study was to examine whether MIF expression is up-regulated in allograft rejection and whether MIF expression is associated with the rejection process. To this end, we investigated MIF expression in renal biopsies from patients with kidney allo- graft rejection. 1 Presented in part at the XIVth International Congress of Ne- phrology, May 1997, Sydney, Australia, and at the XVII World Con- gress of the Transplantation Society, July 1998, Montreal, Canada, 1998. 2 This work was supported by National Health and Medical Re- search Council grant 960106 and National Institutes of Health grant 13591, and by funding from Merck Sharp & Dohme (toward the costs of color publication). 3 Department of Nephrology, Monash Medical Centre. 4 Address correspondence to: Hui Y. Lan, M.D, Ph.D., Department of Nephrology, Monash Medical Centre, Clayton Road, Clayton, Vic- toria 3168, Australia. E-mail: Huilan@its-mmcc1.cc.monash.edu.au. 5 Picower Institute for Medical Research. * Abbreviations: DTH, delayed-type hypersensitivity; mAb, mono- clonal antibody; MIF, macrophage migration inhibitory factor; PAS, periodic acid-Schiff; PBS, phosphate-buffered saline. 1465