HLA-DR Immunohistochemistry Quantitation in Renal Allograft Biopsies: Objective Discrimination of Rejection and Other Pathologic Processes.
Alton B Farris, Jun Kong, Candace Chisolm, Howard M Gebel, Robert A Bray, Cynthia Cohen, Daniel J Brat, Joel H Saltz, Allan D Kirk, Randolph Hennigar. Emory University, Atlanta, GA; Emory University, Atlanta
Background: Histologic renal allograft biopsy (bx) assessment methods (e.g., the Banff criteria), although historically useful, largely rely on semi-quantitative, granular criteria, sometimes making the appreciation of subtle pathologic differences difficult. Human leukocyte antigen (HLA)-DR expression has been shown in renal allografts, particularly bxs with rejection. We investigated the utility of renal allograft bx assessment using HLA-DR immunohistochemistry (IHC) whole slide image (WSI) analysis.
Design: IHC was performed with a commercially-available HLA-DR antibody on bxs containing allograft rejection, polyomavirus nephritis (PVN), a borderline pattern, normal donor tissue, and stable allografts. HLA-DR WSIs obtained using an Olympus Nanozoomer scanner were quantitated with regard to total and cortical renal parenchymal staining using the Aperio Imagescope Positive Pixel Count algorithm, yielding a % of parenchyma with HLA-DR positivity.
Results: Highest HLA-DR positivity was seen in allograft rejection bxs [Table]. Elevated levels were also seen in PVN, followed by borderline cases. A baseline HLA-DR level was present in normal donor bxs, and the lowest levels were in stable allografts. Differences were not significant between rejection and polyomavirus nephritis; however HLA-DR levels in rejection and PVN were significantly higher than stable and normal donor bxs. Rejection but not PVN was significantly higher than borderline. Linear regression showed a direct correlation between total and cortical HLA-DR (R2 = 0.98, P < 0.0001).
|Type||HLA-DR total parenchymal positivity (%) [Mean ± S.D.]||Comparison (T-test)|
|Rejection (n = 15)||62.2 ± 16.2||***, *, •|
|Antibody-mediated rejection (n=3)||68.6 ± 9.3||***, *, •|
|Cellular rejection (n =12)||60.6 ± 17.4||***, *, •|
|PVN (n = 3)||60.6 ± 8.1||**, ^|
|Borderline (n = 2)||36.1 ± 10.4|
|Normal donor (n = 4)||33.6 ± 18.5|
|Stable allograft (n =3)||15.0 ± 4.4|