[1534] Correlation of Histologic Findings with Donor Specific Antibodies (DSA) in C4d Positive Renal Allograft Biopsies during the Early Post-Transplant Period

MF Palma Diaz, N Kieran, N Leca, P Warner, K Nelson, CL Davis, KD Smith, RF Nicosia, CE Alpers, J Kowalewska. University of Washington, Seattle, WA; Puget Sound Blood Center, Seattle, WA

Background: Peritubular capillary (PTC) deposition of C4d is considered to be immunopathologic evidence of antibody reactivity and one of the criteria for diagnosis of acute antibody mediated rejection. In cases without morphologic evidence of active rejection, the significance of C4d is unknown. In this study, we correlate histologic findings with presence of anti-HLA DSA in patients (pts) with PTC C4d.
Design: We searched our database for renal allograft bx that were obtained up to 3 months post-transplantation and showed diffuse staining of PTC for C4d, detected by either IF or IP. Sera were tested for DSA, and their antigenic specificity was recorded. Bx were grouped by histologic findings according to Banff criteria, and correlated with DSA.
Results: 32 pts met the entry criteria. The average time post-transplantation was 25 days (range, 7-70). The cases were divided into groups with: no significant changes (n=19), borderline lesions (n=3), ACR (n=8), and isolated TMA (n=2). The correlation between histologic findings and presence of DSA (Table 1), and histologic findings and DSA specificity (Table 2) is shown below.

Table 1
n (%)n (%)n (%)n (%)n (%)
DSA +12 (63.2)2 (66.67)6 (75)2 (100)10 (76.9)
DSA -7 (36.8)1 (33.3)2 (25)0 (0)3 (23.1)
TOTAL19 (59.4)3 (9.4)8 (25)2 (6.2)13 (40.6)

Table 1
No tissue injuryBorderlineACRTMA
class Iclass IIclass Iclass IIclass Iclass IIclass Iclass II
CW02, B61DR17DQ02A31B60, CW10
DQ02DR13DR13DR16,51, DQ05
B08,61DQ02, DR11DQ09
DQ9CW01DP4, 13
DR08, DQ04A25, B07
A02DQ02, PD0201

Conclusions: In our study 19/32 (59.4%) patients with PTC C4d did not have acute rejection or other graft pathology, and of these 7 (36.8%) did not have circulating DSA. In contrast, the great majority of pts with PTC C4d and tissue injury had circulating DSA (10/13, 76.9%). When DSA are identified, the groups with rejection/tissue injury appear to have different antigenic specificity than those without.
Category: Kidney (does not include tumors)

Wednesday, March 24, 2010 1:00 PM

Poster Session VI # 224, Wednesday Afternoon


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