Renal Allograft Plasma Cells, B Cells, Banff Grade and Outcome
R John, AM Herzenberg. University Health Network and Univeristy of Toronto, Toronto, ON, Canada
Background: Recently, interest has been generated in the presence of plasma cells and B cells in renal allograft rejection, but their role remains unclear. In particular, this includes the intragraft relationship between these cells, and whether these cells contribute to acute cellular rejection (ACR), acute humoral rejection (AHR), or both. Some association with poor outcome has been shown. Our aim was to examine the association, if any, between plasma cells and B cells, their relationship with the type of rejection, and whether an assessment of their presence is useful as a determinant of outcome.
Design: We identified all cases of acute rejection between 2005 and 2009 accompanied by noticeable (≥ 5%) plasma cell infiltrates (n=23), and selected 10 cases of varying grades of acute cellular rejection as controls. Histopathology, C4d by immunofluorescence, B and T cells by immunohistochemistry (CD20 and CD3 respectively), and graft outcome were evaluated.
Results: Significant plasma cell infiltrates as part of acute rejection were seen in biopsies performed from 24 days to 7.5 years (median, 20 months) after transplant; 7 cases had 5-15% plasma cells, while the remaining 16 cases had ≥25% plasma cells (plasma cell rich [PCR]). Seventeen cases were Banff-Grade 1, and 6 cases were Grade 2. Ten cases had concomitant AHR. T cells accounted for most of the lymphocytic infiltrate in all cases. B cells ranged from 1 to 30% both in cases with and without plasma cells. Higher percentages of B cells were seen when aggregates of lymphocytes were present, whether of a follicular nature or not. Extranodular B cells varied from 1 to 7%, and were always ≤2% of the total infiltrate when aggregates were absent. Eleven grafts were lost at a mean of 3.5 years after transplant. C4d positivity, PCR-ACR and increased B cells were associated with poor outcome, although independent association was seen only with C4d and PCR-ACR.
Conclusions: Plasma cell rich rejection has a poor outcome independent of the Banff grade of rejection. The frequent presence of concomitant AHR may suggest a pathogenetic link. Increased B cells are suggested by the presence of lymphocytic aggregates on H&E stain, although the understanding of intragraft B cells remains unclear.
Category: Kidney (does not include tumors)
Wednesday, March 24, 2010 1:00 PM
Poster Session VI # 223, Wednesday Afternoon