Increased Circulating T Lymphocytes Expressing HLA-DR in Kidney Transplant Recipients with Microcirculation Inflammation

Abstract

We consecutively enrolled 82 kidney transplant recipients (KTRs) with stable renal function and 24 KTRs who underwent indication biopsy to compare the histological grading of renal allografts with the activity of circulating T lymphocyte subsets and monocytes determined by flow cytometry, which were obtained at 2 weeks after kidney transplantation (KT) and at the time of indication biopsy, respectively. The sum of the scores of glomerulitis (g) + peritubular capillaritis (ptc), inflammation (i) + tubulitis (t), interstitial fibrosis (ci) + tubular atrophy (ct), and fibrointimal thickening (cv) + arteriolar hyaline thickening (ah) was used to assign a histological grade to the renal allograft samples. The frequencies of CD4⁺HLA-DR⁺/CD4⁺ T cells and CD8⁺HLA-DR⁺/CD8⁺ T cells were significantly increased in KTRs with a microcirculation inflammation (MI) sum score ≥ 1 when compared with KTRs with an MI sum score = 0 as well as stable KTRs. In these 2 subsets, only CD4⁺HLA-DR⁺/CD4⁺ T cells were positively correlated with MI sum scores. Analysis using the receiver operating characteristic (ROC) curve showed that antibody-mediated rejection (AMR) could be predicted with a sensitivity of 80.0% and a specificity of 94.7%, using a cutoff value of 29.6% frequency of CD4⁺HLA-DR⁺/CD4⁺ T cells. MI was significantly associated with an increased frequency of activated T lymphocytes expressing human leukocyte antigen-antigen D related (HLA-DR). Further studies should focus on validating the utility of circulating CD4⁺HLA-DR⁺/CD4⁺ T cells as a noninvasive, immunologic monitoring tool for the prediction of AMR.

Keywords: Antibody-Mediated Rejection; Kidney Transplantation; Microcirculation Inflammation; T Lymphocyte.

Fig. 1

Comparisons of T lymphocyte subsets and HLA-DR-positive monocyte between the stable KTRs and 2 groups of KTRs according to the sum scores of MI. The frequencies of CD4⁺HLA-DR⁺/CD4⁺ T cells and CD8⁺HLA-DR⁺/CD8⁺ T cells at the time of biopsy were significantly increased in KTRs with MI sum score ≥ 1 (n = 13) in KTRs with an MI sum score = 0 (n = 11; P = 0.018 and P = 0.037, respectively) as well as KTRs in the normal control group (P = 0.015 and P = 0.038, respectively). HLA-DR = human leukocyte antigen-antigen D related, KTRs = kidney transplant recipients; MI = microcirculation inflammation, DR = antigen D related, MFI = mean fluorescence intensity. ^*P < 0.05.

Fig. 2

Comparisons of T lymphocyte subsets and HLA-DR-positive monocytes between 2 groups according to the sum scores of i + t, ci + ct, and cv + ah. When 2 groups were categorized according to the sum scores of i + t, ci + ct, and cv + ah, serum T lymphocyte subsets and HLA-DR positive monocytes showed no significant differences between 2 groups. HLA-DR = human leukocyte antigen-antigen D related, i = inflammation, t = tubulitis, ci = interstitial fibrosis, ct = tubular atrophy, cv = fibrointimal thickening, ah = arteriolar hyaline thickening, DR = antigen D related, MFI = mean fluorescence intensity.

Fig. 3

Intraluminal cell types in glomeruli and peritubular capillaries by immunohistochemistry. (A-D) Representative figures for CD3⁺ T cells (A) and CD68⁺ macrophages (B) in AMR with MI ≥ 2 and CD3⁺ T cells (C) and CD68⁺ macrophages (D) in TCMR with MI ≥ 2 (immunoperoxidase, original magnification × 200). (E) Comparisons of mean numbers of positive cells for CD3 and CD68 in glomerular and peritubular capillaries in biopsies with AMR with MI ≥ 2 (n = 4) versus TCMR with MI ≥ 2 (n = 4) versus TCMR with MI = 0 (n = 1). The average numbers of CD3⁺ T cells and CD68⁺ macrophages were significantly increased in TCMR with MI ≥ 2 biopsies (P = 0.029) and AMR with MI ≥ 2 biopsies (P = 0.029), respectively. AMR = antibody-mediated rejection, MI = microcirculation inflammation, TCMR = T cell mediated rejection.

Fig. 4

Analysis using the ROC curve. AMR could be predicted with a sensitivity of 80.0% and a specificity of 94.7% using a cutoff value of 29.6% frequency of CD4⁺HLA-DR⁺/CD4⁺ T cells. The areas under the curve of circulating CD4⁺HLA-DR⁺/CD4⁺ T cells for predicting AMR was 0.874. ROC = receiver operating characteristic, AMR = antibody-mediated rejection.