Transplant glomerulopathy [TG] has a very poor prognosis and is almost always associated with eventual graft failure. The risk of TG is increased in patients who have experienced acute rejection or have had evidence of microcirculatory inflammation. The Banff classification stipulates that glomerulitis [GL] is a lesion predominantly associated with AMR. However GL occurs in acute cellular rejection [ACR] although its significance is not well described.

The purpose of this study was to establish the significance of GL in patients with ACR.

147 cases of ACR [m104, f43, 67 LDs, 80 DCDs, mean HLA mm 3.44 ± 1.67], as classified by Banff 2007, with predominant tubulo-interstitial rejection were analyzed. The mean follow up post biopsy was 2.74 ± 1.55 years. All patients had received monoclonal antibody induction with tacrolimus based maintenance immunotherapy and corticosteroids for one week only.

Patient and allograft survival was 94.2% and 82.5% at 2yrs post biopsy. 27/147[18.4%] patients had glomerulitis. GL was not associated with allograft failure, HR 0.89 (0.37-2.13), p=0.80; further episodes of TCMR, HR 0.93 (0.50-1.74), p=0.83 or AMR, HR 0.64 (0.18-2.23), p=0.48.

However GL was associated with risk of the development of TG, HR 10.67 (3.07-37.08), p=0.0002. Glomerular immunohistochemistry staining showed that 8/25 (32.2%) cases were CD3+ alone, 6/25 (24.0%) were CD68+ alone and 13/27 (48.1%) had both CD3+ and CD68+ cells. Only patients with CD68+ cells were at risk of developing TG, with TG free survival in the GL negative group, CD3+ group, CD68+ group and CD3+/CD68+ group being 90.0%, 87.5%, 44.4% and 45.5% respectively, p=0.0002 as shown in figure 1.

Pure CD68+GL was strongly associated with the presence of donor specific antibodies [DSA] with 5/6 [83.3%] having DSA.

This study shows the importance of determining the type of infiltrating cell in GL. CD68+ cells herald the development of TG and a preemptive increase in immunosuppression may be preventative.

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