[1665] The Significance of Tubuloreticular Inclusions (TRIs) in Allograft Kidney Biopsies

Carla L Ellis, Gaurav Gupta, Lorraine C Racusen, Lois J Arend. The Johns Hopkins Hospital and School of Medicine, Baltimore, MD

Background: Tubuloreticular inclusions (TRIs) consist of anastomosing tubular structures found within the endothelial cells of glomerular and peritubular capillaries. Historically, they have been referred to as interferon footprints, as they are inducible in normal lymphocytes upon exposure to interferon alpha in vitro. Although their precise function or cause remains unknown, it has been reported that they can be seen in native kidneys of patients with lupus nephritis, human immunodeficiency virus infection, and in patients treated with interferon. A previous report showed that in transplanted kidneys, the presence of TRIs was second only to lupus nephritis in terms of total amount, and suggested that their presence in transplants may be associated with procedural ischemia, and not a viral etiology. Our study strives to further determine the significance of TRIs in transplant biopsies.
Design: A search of our computer database revealed renal allograft biopsies in which TRIs were clearly identified as present (n=28) between the period of Jan '08 - Oct' 11. A control group in which TRIs were not described was identified (n=48). A descriptive analysis of patient and biopsy characteristics for the TRI group was performed. The TRI group was compared with the control group for prevalence of viral infections including parvovirus, hepatitis C, hepatitis B and adenovirus, and other clinical and pathologic characteristics.
Results: Only 2 patients in the TRI group had 'classic' pre-transplant associations with TRIs (one each for HIV and lupus). A sizeable proportion (11/28; 40%) of biopsies was obtained from 'high-risk' transplant recipients (ABO incompatible and/or positive-crossmatch). 11/28 (39%) biopsies had some form of allograft rejection based upon Banff criteria. In comparison with the control group (1/48; 2%), the TRI group had a significantly higher prevalence of hepatitis C infection (6/28; 21%), only one of which had been treated with interferon. This latter finding was statistically significant (p=0.008).
Conclusions: Based upon our preliminary findings, it appears that the presence of TRIs in renal allograft biopsies is not explained adequately by traditionally reported associations (HIV, lupus or interferon therapy). A diagnosis of hepatitis C should be sought in renal allograft biopsies with demonstrable TRIs. Further analyses are needed to find other putative etiologies for the presence of TRIs, including the observed intriguing preponderance in 'high-risk' renal allografts.
Category: Kidney (does not include tumors)

Wednesday, March 21, 2012 1:00 PM

Poster Session VI # 278, Wednesday Afternoon


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