[1527] Immunophenotyping Interstitial Inflammatory Cells in Acute Rejection

JM Moore, J Williams, J Du, SR Marino, SM Meehan, A Chong, A Chang. University of Chicago Medical Center, Chicago, IL

Background: The potential role of B lymphocytes and plasma cells (PCs) in antibody-mediated (humoral) rejection is gaining attention, but remains poorly understood. We hypothesize that significant accumulation of intraparenchymal B and PCs may occur in acute antibody-mediated rejection and attempt to characterize the infiltrate in a different manner than those in the literature.
Design: We searched our pathology archives from 2005-2009 and identified 57 human renal biopsies with a diagnosis of acute rejection. The biopsies were divided into 3 groups: 1) cell-mediated rejection only; 2) antibody-mediated rejection only (with positive C4d peritubular capillary deposition); and 3) both cell- and antibody-mediated rejection. Standard immunohistochemistry was performed on paraffin tissue sections using monoclonal antibodies to CD20, CD138, CD3 and CD45 (DAKO, Carpinteria, CA). The number of interstitial cells with strong membranous staining was counted for each antibody and the percentage of positive cells was calculated using the total positive CD45 cells as the denominator. This data was correlated with clinical information, biopsy diagnosis, and presence of HLA antibodies. Statistical analysis was performed using the Mann-Whitney or Kruskal-Wallis test with p<0.05 considered as significant.
Results:

Immunophenotype of interstitial inflammatory cells

Rejection type	CD20%	CD138%	CD3%	# of cases
Cell-mediated	13.6%	5.1%	75.6%	21
Antibody-mediated	13.0%	6.9%	57.4%	15
Cell- and antibody-mediated	15.7%	15.8%	57.9%	21
C4d positive	14.7%	11.9%	57.2%	30
C4d negative	12.3%	5.2%	75.8%	27
HLA class I/II abs present	11.1%	10.8%	66.8%	27
No HLA class I/II abs	25.9%	1.5%	78.6%	4

The average percentage of PCs in biopsies with or without C4d peritubular capillary deposition was 11.9% and 5.2%, respectively (p=0.01). The combined cell- and antibody-mediated rejection biopsies demonstrated more than twice as many PCs than the other two groups (p=0.008). The average percentage of PCs in patients with the presence or absence of anti-HLA class I or II antibodies was 10.8% and 1.5%, respectively (p=0.03).
Conclusions: Significantly increased percentages of interstitial PCs were observed in renal biopsies with both cell- and antibody-mediated rejection, presence of C4d peritubular capillary deposition, and presence of HLA class I or II antibodies. Intrarenal PCs deserve further attention to understand their potential role in antibody-mediated rejection.
Category: Kidney (does not include tumors)

Wednesday, March 24, 2010 1:00 PM

Poster Session VI # 222, Wednesday Afternoon