Background: Antibody-mediated rejection manifests with glomerular and peritubular capillary inflammation, transplant glomerulopathy. Transplant glomerulitis is an increasingly recognized lesion in renal transplant biopsies, characterized by the influx of lymphomononuclear cells and swelling of endothelial and mesangial cells of glomerular. The aim of our study was to analyze the cellular composition of inflammatory cell infiltrates in glomerulitis and to determine whether it is associated with antibody-mediated rejection.

Design: We retrospectively reviewed IHC staining for macrophages (CD68) and T lymphocytes (CD3) on 85 renal transplant recipients at MWHC between 2011 and 2014. We studied glomerulitis by counting the number of intraglomerular macrophages and T cells and examined C4d deposition, circulating DSA and degree of acute T-cell mediated rejection.

Results: Comparison was made among control group (C4d-/DSA-/ACH-), T-cell mediated rejection only group (C4d-/DSA-/ACH+), antibody-mediated rejection only group (C4d+/DSA+/ACH-), and mixed-rejection group (C4d+/DSA+/ACH+). Compared with controls, biopsies with pure antibody-mediated rejection group had more intraglomerular inflammatory cells (macrophages, 8.96 ± 5.87 versus 1.81± 1.9 cells/glomerulus, P < .05, T lymphotcytes, 3.35 ± 2.44 versus 0.81± 1.09 cells/glomerulus, P < .05). Compared with pure T-cell mediated cellular rejection group, biopsies with mixed-rejection group had more intraglomerular inflammatory cells (Macrophages, 11.19 ± 5.87 versus 3.33± 3.44 cells/glomerulus, P < .05, T lymphotcytes, 5.99± 3.35 versus 2.15± 2.33 cells/glomerulus, P < .05). No difference in intraglomerular macrophages and T lymphocytes was observed between T-cell mediated rejection only group and control group, and between mixed-rejection group and antibody-mediated rejection only group. There is no difference between DSA+C4d-ACR- and DSA-C4d-ACR- group.

Conclusions: Transplant glomerulitis is significantly correlated with antibody-mediated rejection but not cellular rejection. DSA alone does not correlate with glomerulitis in the absence of antibody-mediated humoral rejection and C4d deposition. The macrophages and T lymphocytes are the main inflammatory cells in the glomerulitis of antibody-mediated rejection. Detection of glomerulitis by T-cell and macrophage infiltrate in renal allografts will be helpful for a diagnosis of antibody-mediated rejection, especially in cases difficult to establish a diagnosis by morphology.

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