Elsevier

Transplant Immunology

Volume 15, Issue 1, October 2005, Pages 63-68
Transplant Immunology

C4d deposition in lung allografts is associated with circulating anti-HLA alloantibody

https://doi.org/10.1016/j.trim.2005.05.001Get rights and content

Abstract

The complement activation demonstrated by vascular C4d deposition is used to diagnose antibody-mediated rejection (AMR) in renal allografts, but remains controversial in lung transplantation (LTX).

Methods

C4d deposition was assessed by immunohistochemistry in 192 lung transplant biopsies from 32 patients. ELISA analysis was performed on 415 serum samples in those 32 temporally and rejection-grade matched LTX patients; 16 patients developed HLA-Ab, while the other 16 patients remained negative. The specificity of C4d staining was further compared in 18 additional LTX patients without HLA-Ab or acute cellular rejection (ACR), but in the presence of CMV-pneumonitis or reperfusion injury.

Results

Specific subendothelial C4d deposition was seen in 5 of 16 (31%) patients with HLA-Ab and was absent in 16 patients without HLA-Ab (p < 0.05). All patients with specific C4d deposition exhibited donor-specific HLA-Ab. There were 13 patients with bronchiolitis obliterans syndrome in the group of 16 HLA-Ab positive patients, versus 2/16 in ELISA-negative patients (p < 0.005). One of 7 patients with CMV pneumonitis and 2 of 11 patients with reperfusion injury also showed C4d positivity (not statistically significant).

Conclusions

In this study, specific subendothelial C4d deposition was a marker for the involvement of HLA-Ab in lung allograft rejection. The patchy nature, low sensitivity, and specificity of C4d staining might limit clinical use in protocol biopsies. However, in patients with decreasing pulmonary function, refractory ACR and/or HLA-Ab, specific C4d deposition may serve as a marker of coexistent AMR.

Introduction

Acute cellular rejection (ACR) is considered the most important independent risk factor for the development of chronic rejection and graft loss in lung transplantation (LTX) [1], [2], [3]. The “gold standard” for diagnosis of ACR is perivascular lymphocytic infiltration, while the pathogenic role of antibody-mediated rejection (AMR) alone or in conjunction with cellular rejection is less well documented [4].

We have previously reported that the development of anti-HLA alloantibody (HLA-Ab) was associated with high-grade and refractory ACR, lymphocytic bronchiolitis, and increased use of cytolytics and/or immunosuppressive therapy [5], [6]. Furthermore, we and others described significant associations between HLA-Ab and bronchiolitis obliterans syndrome (BOS) [6], [7], [8], [9], [10], [11], [12]. However, a statistical association does not imply a cause–effect relationship.

Section snippets

Objective

C4d is a tissue marker for antibody-mediated rejection in kidney allografts, but its association with HLA-Ab has not been documented in LTX [13], [14], [15]. We have previously found increased soluble C4d in the bronchial lavage of LTX patients with HLA-Ab [16].

In the current study, we investigate C4d deposition in lung allograft biopsies from patients with or without circulating IgG HLA-Ab.

Materials and methods

Thirty-two patients who received lung transplantation between 1999 and 2002 and had at least 2 years of follow-up were included in the study. The Institutional Review Board of the University of Pittsburgh approved the protocol and informed consent was obtained from all patients.

Antibody detection

After the analysis of 415 serum samples for the presence of HLA-Ab in 32 lung allograft recipients, 16 patients exhibited multiple positive results, while 16 patients remained ELISA-negative. In 65% of cases, the first detection of HLA-Ab was in the first 6 months after transplantation, while one third appeared between 6 months and 2 years post-LTX. The donor specificity of HLA-Ab was proved in 8 out of 16 patients (50%).

Acute and chronic rejection in patients with or without HLA-Ab

No differences were seen between the histological features of ACR in

Discussion

In this study, we describe the specific C4d staining pattern in lung allografts, the sensitivity and specificity of C4d immunohistochemical stain in paraffin-embedded tissue, and its association with circulating HLA-Ab.

The specific C4d deposition in kidney allografts is considered as continuous, linear subendothelial staining of peritubular capillaries and is incorporated into the Banff classification [15], [21]. Similarly, in lung allografts, we considered specific the continuous, linear,

References (33)

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This work was partially supported by NIH grant HL-65189.

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