Immunohistochemical staining for proliferation antigen as a predictor of chronic graft dysfunction and renal graft loss

Histological characteristics of Acute Tubular Injury during Delayed Graft Function predict renal function after renal transplantation

Acute Tubular Injury (ATI) is the leading cause of Delayed Graft Function (DGF) after renal transplantation (RTX). Biopsies taken 1 week after RTX often show extensive tubular damage, which in most cases resolves due to the high regenerative capacity of the kidney. Not much is known about the relation between histological parameters of renal damage and regeneration immediately after RTX and renal outcome in patients with DGF. We retrospectively evaluated 94 patients with DGF due to ATI only. Biopsies were scored for morphological characteristics of renal damage (edema, casts, vacuolization, and dilatation) by three independent blinded observers. The regenerative potential was quantified by tubular cells expressing markers of proliferation (Ki67) and dedifferentiation (CD133). Parameters were related to renal function after recovery (CKD-EPI 3, 6, and 12 months posttransplantation). Quantification of morphological characteristics was reproducible among observers (Kendall's W ≥ 0.56). In a linear mixed model, edema and casts significantly associated with eGFR within the first year independently of clinical characteristics. Combined with donor age, edema and casts outperformed the Nyberg score, a well-validated clinical score to predict eGFR within the first year after transplantation (R2  = 0.29 vs. R2  = 0.14). Although the number of Ki67+ cells correlated to the extent of acute damage, neither CD133 nor Ki67 correlated with renal functional recovery. In conclusion, the morphological characteristics of ATI immediately after RTX correlate with graft function after DGF. Despite the crucial role of regeneration in recovery after ATI, we did not find a correlation between dedifferentiation marker CD133 or proliferation marker Ki67 and renal recovery after DGF.

Expression of matrix metalloproteinase-9 and significance of a macrophage assay in eosinophilic granuloma

Although most cases of eosinophilic granuloma (an immune-mediated lesion) do not behave in an aggressive manner, occasionally, recurrence after treatment has been observed. This study aims to investigate the significance and relationship of matrix metalloproteinase-9 (MMP-9) and infiltration of macrophages in eosinophilic granulomas (EGs). The immunohistochemical strept avidin-biotin complex method was used to detect the expression of MMP-9 and CD-68 (for labeling macrophages) in 13 cases of EG. Three of whom showed local recurrence. The results showed that many of the Langerhans histiocytic cells, which reacted positively with MMP-9 protein antibody, were immunolabeled with CD-68 antibody. The results showed that there is a highly significant relationship between the expression of MMP-9 and macrophage count in EGs (P < .001), with recurrent lesions showing a higher mean expression of both MMP-9 and CD-68. In conclusion, there may be a cooperation between macrophages and MMP-9 in EGs, which correlates well with local recurrence. Their expression may therefore provide some prognostic indication of the possible aggressive and recurrence behavior of this lesion.

Lymphoid cell proliferation in renal transplants: biologic and diagnostic implications

It is unclear whether alloreaction develops in peripheral lymphoid organs and effector cells being recruited to the target organs, or the entire process of alloreaction can happen within the transplanted kidneys. Interstitial inflammatory cell (IIC) proliferation was evaluated by MIB-1 antigen immunostain and the rate expressed as positive cells/1000 cells. This rate was higher in acute cell-mediated rejection (ACR) (25.7, n = 14) compared with normal kidney (0.4, n = 8), acute tubular necrosis (1.2, n = 8), chronic allograft nephropathy (CAN, 2.4, n = 20), and native kidneys with diverse diseases (9.2, n = 63); but was comparable to that in CAN with significant IIC (20.6, n = 16). 10.1% and 8.3% of T lymphocytes underwent proliferation in ACR with or without CAN, whereas only rare B lymphocytes or macrophages showed this change (<1.2%), regardless of diagnostic categories. All biopsies diagnosed as ACR in conjunction with a high rate of MIB-1 + IIC and 9/12 biopsies with CAN and significant IIC in which ACR was diagnosed due to a high rate of MIB-1 + IIC, responded to anti-rejection therapy. Proliferation of IIC involves predominantly T lymphocytes. These observations provide support for the concept of in situ alloimmunization, and facilitate the diagnosis of ACR.