Transcript Slide 1

The Significance of C4d
Staining with Minimal
Histologic Abnormalities
Mark Haas
Department of Pathology
Cedars-Sinai Medical Center
Los Angeles, California, USA
Outline/Objectives
1. To appreciate differences in the interpretation of
positive C4d staining in ABO-incompatible renal
allografts versus conventional and positive crossmatch (HLA-incompatible) renal allografts
2.
To review potential prognostic implications of C4d
staining without histologic lesions of antibodymediated or cellular rejection in ABO-incompatible
versus conventional and positive cross-match
renal allografts
C4d
• Degradation product of complement factor C4, a component
of the classical complement pathway that is typically
initiated by antibody bound to antigen
• After cleavage of remaining C4 domains, C4d remains
covalently bound at site of C4 activation
• Thus, C4d is a relatively long-lived marker of a humoral
response
• Easily detected in tissue sections by immunofluorescence
or immunohistochemistry
C4d Staining in Renal Allografts:
correlation with donor-specific Ab
• Collins et al, JASN 10: 2208-14, 1999
100% of AR with +DSA were C4d+
No C4d in DSA- AR, CSA toxicity
• Crespo et al, Transplantation 71: 652-8 2001
18/19 with steroid-resistant AR and DSA C4d+
2/32 with steroid-resistant AR and no DSA C4d+
C4d positivity 95% sensitive for presence of DSA (IF)
• Maueyyedi et al, JASN 13: 779-787, 2002
30% of early AR C4d+ - 90% had anti-donor antibody
2 morphologic subtypes of AMR - capillary, arterial
Arterial had worse outcome
• Bohmig et al, JASN 13: 1091-9, 2002
21/24 C4d+ cases had DSA by flow cytometric XM
50% of C4d- biopsies had DSA
93% specificity, 31% sensitivity (IHC on paraffin sections)
Diagnostic Criteria for Acute AMR in
Renal Allograft Biopsies
(L.C. Racusen et al, Am J Transplant 3: 1-7, 2003)
1. Morphologic evidence
a. Neutrophils and/or monocytes/macrophages in PTC
and/or glomeruli (acute glomerulitis)
b. Arterial fibrinoid necrosis
c. Thrombi in glomerular capillaries, arterioles, and/or
small arteries
d. Acute tubular injury (?)
2. Immunohistologic evidence
a. C4d in PTC
b. Immunoglobulin and/or complement in arterial
fibrinoid necrosis
3. Serologic evidence
a. Circulating antibodies to donor HLA or other specific antidonor antibodies at the time of biopsy
RN Smith et al, AJT 8: 1662-72, 2008
No TG
TG
Cosio et al, AJT 8:492-6,2008
What is the effect of C4d staining
without histologic evidence of AMR in
ABO-I grafts?
44 recipients of ABO-I grafts 1/00 – 6/07
37 met the following criteria:
1. One or more protocol biopsies were done during
the first ~3 months post-transplantation, meeting
Banff ’97 adequacy criteria
2. One or more subsequent protocol biopsies were
done at 6 and/or 12 months post-transplantation,
meeting the same adequacy criteria
3. C4d staining was done on all protocol biopsies
What is the effect of C4d staining without histologic
evidence of AMR in ABO-I grafts?
Of these 37 patients:
21 (Group A) had an initial (1 or 3 month) protocol biopsy
meeting all of the following criteria:
•
•
•
>1+ diffuse PTC C4d
No ACR (Banff ’97 1a or greater) or histologic evidence of AMR
(PTC neutrophil or mononuclear WBC margination [ptc >0],
glomerulitis [g>1], TMA, or arterial/arteriolar fibrinoid change)
Presence of circulating antibody against donor blood group
antigen(s)
Of remaining 16 patients, 12 had negative or focal and weak (<1+)
PTC C4d on their initial protocol biopsy (Group B), while the
other 4 had >1+ diffuse C4d but with PTC WBC margination (SC
AMR; omitted). All had circulating anti-blood group antibody. No
patient had anti-HLA Class I or Class II antibodies.
Demographic and Serologic Data in Patient Cohorts
Number of patients
Age (years, mean + SD)
Males/Females
Race (white/black/Hispanic)
Group A (C4d+)
Group B (C4d-)
21
12
49 + 12
54 + 13
0.25
12/9
8/4
0.72
18/3/0
9/2/1
0.58
Donor blood group type:
P Value
0.09
A1
14
4
A2
2
1
A1B
1
1
B
3
6
182 + 217
133 + 134
0.51
Pre-transplant (mean + SD)
6.1 + 2.3
5.8 + 2.4
0.48
Post-transplant (mean + SD)
4.7 + 1.5
4.7 + 2.1
0.74
Splenectomy
4
3
Anti-CD20
4
2
Splenectomy and anti-CD20
1
0
None
12
7
Initial BG Ab titer (mean + SD)
Number of PP/IVIG treatments:
Other pre-transplant treatments
Clinical Findings in Patient Cohorts
Group A (n = 21)
Group B (n = 12)
P Value
49 + 29
44 + 18
0.90
852 + 515
887 + 218
0.53
At diag./initial biopsy (mean + SD)
1.2 + 0.3
1.2 + 0.4
0.84
At 6 mo protocol bx (mean + SD)
1.3 + 0.2
1.4 + 0.5
0.50
At 12 mo protocol bx (mean + SD)
1.3 + 0.3
1.4 + 0.7
0.65
At most recent F/U (mean + SD)
1.3 + 0.3
1.3 + 0.2
0.59
1 (5%)
2 (17%)
0.54
Post-transplant day of initial
protocol biopsy (days, mean + SD)
Post-transplant day of most
recent F/U (days, mean + SD)
Serum creatinine (mg/dL):
Graft losses
Renal Findings in Patient Cohorts
Group A (n = 21)
Group B (n = 12)
P Value
Number (%) of Pts. With AMR
(all were clinical)
1 (5%)
3 (25%)
0.12
Number (%) of Pts. With ACR
(including clinical and subclinical)
7 (33%)
4 (33%)
0.99
ACR Type (Banff ’97)
0.82
None or borderline
14
8
1A
0
1
1B
2
1
2A
5
2
Number (%) of Pts. With BKV
5 (24%)
2 (17%)
0.99
No. (%) of Pts. with Recurrent FSGS
1 (5%)
1 (8%)
0.99
At diag./initial biopsy (mean + SD)
1.52 + 1.29
1.33 + 1.37
0.72
At 6 mo protocol bx (mean + SD)
1.86 + 1.82
3.00 + 2.57
0.22
At 12 mo protocol bx (mean + SD)
2.42 + 1.26
3.89 + 2.42
0.032
(cg + ci + ct + cv):
Dickenmann et al, Clin Nephrol 65: 173-179, 2006
• Examined outcomes in 22 patients having for-cause biopsies of
conventional renal allografts that showed focal (n = 21) or diffuse (n = 1)
peritubular capillary C4d staining by IF, no morphologic evidence of AMR
or ACR, and no prior C4d+ biopsy.
• 5/22 patients received anti-rejection therapy following the biopsy, while
17/22 continued to receive only baseline immunosuppression
Anti-rejection therapy:
Yes
No
P
SCr (mg/dl) at biopsy
1.92 + 0.88
1.95 + 0.62
ns
Lowest SCr within 4 weeks
post-biopsy
0.95 + 0.22
1.60 + 0.54
0.02
SCr 1 year post-biopsy
1.26 + 0.25
2.04 + 0.91
ns
100%
69%
ns
3-year graft survival
+CM
3 month protocol bx
SCr 1.0 mg/dl
2 + diffuse C4d, ptc 3
No ACR
Conclusions
1. Although based on a retrospective analysis of a relatively
small number of patients, our findings suggest that
diffuse PTC C4d deposition and circulating anti-blood
group antibodies in the absence of clinical or histologic
evidence of AMR is most likely associated with a
decreased risk of scarring in ABO-incompatible renal
allografts in the relatively short term.
2. It will be important to determine if this apparent beneficial
effect persists over the long term and in larger cohorts of
patients from different centers. If true, this would indicate
that C4d staining without other evidence of AMR in ABOincompatible grafts most likely represents a state of stable
accommodation.
Conclusions (continued)
3. Unlike the case in ABO-incompatible grafts, in positive
crossmatch (and conventional) renal allografts C4d
deposition in the absence of histologic evidence of AMR
appears to be uncommon, and may in fact indicate
(potentially reversible) graft injury. However, there may be
notable exceptions.
Department of Pathology
Lorraine Racusen
Serena Bagnasco
Karen King
Department of Medicine
Edward Kraus
Hamid Rabb
Andrea Zachary
Hafiz Rahman
Department of Surgery
Robert Montgomery
Dorry Segev
Daniel Warren
Chris Simpkins
Diane Lepley
Jayme Locke