Expression of Carcinoembryonic Antigen-Related Cell Adhesion Molecule 1 in Acute Rejection of Human Renal Allografts

Background: Carcinoembryonic antigen-related cell adhesion molecule 1 (CEACAM1) is expressed on various cell types and mediates homophilic cell adhesion. CEACAM1 plays an important role in cell morphogenesis and angiogenesis. Furthermore, CEACAM1 regulates adhesive activity of immune-competent cells, suggesting an additional role in inflammatory processes. Methods: Therefore, in the present study the expression of CEACAM1 was analysed retrospectively in renal biopsies from kidney transplant recipients (stable graft [Ctr; n = 18], acute vascular rejection [AVR; n = 14], acute tubulointerstitial rejection [AIR; n = 9], and combined vascular and interstitial rejection [AVIR; n = 7]). Expression patterns of CEACAM1 were determined using immunohistochemistry and quantitative morphometry. Results: All biopsy specimens from patients with stable grafts showed low CEACAM1 levels, suggesting a constitutive expression in renal transplants. In patients with acute rejection, CEACAM1 was markedly up-regulated. AVR revealed the highest tubular CEACAM1 levels (4.9 ± 0.5% [AVR] vs 2.2 ± 0.3% [Ctr] of tubular area; P < .05), whereas interstitial rejections showed the highest glomerular expressions (4.5 ± 0.5% [AIR] vs 0.9 ± 0.1% [Ctr] of glomerular area; P < .05). Conclusions: An up-regulated expression of CEACAM1 in tubular and/or glomerular cells is an indicator of acute inflammatory processes in biopsy specimens from patients with acute renal allograft rejections and, therefore, might be used as a new clinical marker.