Immunohistopathologic Characterization of Plasma Cell-Rich Acute Rejection in Living-Related Renal Transplant Recipients.

OBJECTIVES

Our aim was to analyze the immunohistopathologic features of plasma cell-rich acute rejection in a living-related renal transplant setting.

MATERIALS AND METHODS

Renal allograft biopsies of 50 cases of plasma cell-rich acute rejection were reviewed, and the main immunohistopathologic features were analyzed. The biopsies were studied using light microscopy, immunofluorescence, and immunohistochemistry and reported according to Banff classification. Biopsy findings were correlated with graft function and outcome.

RESULTS

From February 2012 to December 2013, 50/1630 (3%) dysfunctional renal allograft biopsies showed plasma cell-rich acute rejection. Among acute changes, interstitial inflammation was of moderate degree in 8 cases (16%) and severe in 42 cases (84%). Mild tubulitis was found in 4 cases (8%), moderate tubulitis in 8 cases (16%), and severe tubulitis in 38 cases (76%). Glomerulitis was found in 2 cases (4%). No presence of arteritis was found. All plasma cell-rich acute rejection cases were of tubulointerstitial type, and most were of type IB. The mean percent of plasma cells on light microscopy in all cases was 28.8 ± 11.7%, and the range was 10% to 60%, with 46 cases (92%) showing plasma cell percent of ≥ 20%. The mean plasma cell percent on immunohistochemistry for CD138 was 29.0 ± 12.4%. Microvascular inflammation was found in 34 cases (68%). C4d testing was done by immunofluorescence in 22 cases (44%) and was positive in 8 cases (36%). Interstitial fibrosis/tubular atrophy was mild in 18 (36%), moderate in 28 (56%), and severe in 4 cases (8%). Plasma cell enrichment did not correlate with a variety of clinical and pathologic features (all P > .05).

CONCLUSIONS

Plasma cell enrichment is not an independent prognostic morphologic feature and may represent either T-cell-mediated or antibody-mediated rejection or a mixture of these processes. Further investigations regarding its pathogenesis, accurate categorization, and treatment are needed.