Prognostic significance of C4-positive vs. negative rejection
Heinz Regele
Department of Pathology
Innsbruck Medical University
C4d-negative rejection
Has all clinical and morphological features of antibody
mediated rejection but lacks C4d in transplant biopsies
Issues to discuss
Clinical relevance (prognosis, diagnostic features)
Biology
Mechanisms of Humoral Allograft Rejection
PMN
T-cell
NK-cell
Mø
Mø
C1
MAC
C3b
C1
C4d
C3b
C4d
MAC
Allograft Endothelial cells
Dual Role of Complement
Biology
C3, C5, C5b-9
Diagnostic marker
C4d (C3?)
C4d
Banff classification of renal allograft rejection
ATN
DSA
C4d
Capillaritis
Arterial necrosis
MHC I
+
+
MHC II
anti-C4d
or
or
% Allograft suvival
Capillary C4d deposition and allograft survival
100
90
80
70
60
50
40
30
20
10
0
C4d- (N=42)
90%
Total (N=93)
72%
C4d (+) (N=8)
63%
C4d+ (N=43)
0
1
2
3
6
4
5
7
Months post TX
57%
8
9
10
11
12
Renal C4d deposits in 93 patients with early allograft dysfunction
Feucht et al, Kidney Int, 43:1333, 1993
C4d staining and FCXM (Flow-Cytometry X-Match) of corresponding sera
113 biopsies of 58 renal allograft recipients
In 2 Patients severe rejection
reversible by IA
4 allografts lost
C4d neg/FCXM neg
N = 20
C4d pos
N = 16
C4d neg/FCXM pos
N = 22
1 allograft lost
G.A. Böhmig et al, JASN 2002
Tissue injury and outcome in DSA positive patients
A. Loupy et al., AJT 2011
Microvascular injury and chronic ABMR
….C4d may not be a sufficiently sensitive indicator of activity, MI and
DSA being more robust predictors of bad outcome.....
A. Loupy et al., AJT 2011
C4d-negative DSA-associated microvascular injury
•Antibody-mediated but complement-independent injury?
•Sampling error?
•Inadequate sensitivity of C4d detection?
•Remnants of previously active ABMR?
Experimental evidence for C4d negative ABMR
Recipients without
adaptive immune system
(RAG1 KO)
MHC incompatible donor
Anti-donor-MHC moAb
Non complement fixing anti donor IgG cause chronic
transplant arteriopathy (CTA). CTA even developed in
RAG1-/-C3-/- double KO mice upon injection of DSA,
strongly suggesting a complement independent
mechanism of injury
T. Hirohasi, AJT 2010
NK cells are essential for the development of DSA
induced CTA in a FcgRIII dependent mechanism (in
absence and presence of complement). DSA alone or in
conjunction with macrophages only do not generate
CTA.
T. Hirohasi, AJT 2012
Jindra PT, Transplantation 2006
Current Opinion in Organ Transplantation 2010; 15: 42-48
Expression of endothelial cell associated transcripts (ENDATs) is present in all
types of rejection but significantly higher in ABMR.
Only 13/50 (26%) of kidneys with high ENDATs and DSA were C4d positive
Only 38% of kidneys with high ENDATs and DSA that subsequently developed
chronic ABMR were C4d positive
Reduced graft survival in C4d-negative ABMR
A: DSA
E: ENDAT
C: C4d
B. Sis et al., AJT 2009
C4d negative ABMR – the clinical approach
What is the prevalence of DSA in C4d negative (micro)vascular injury in
the general population (of TX-recipients)?
What is the clinical course of C4d negative rejection without specific
treatment?
Which diagnostic features are associated with progression to chronic
AMR and/or graft loss?
Prevalence of alloantibodies in C4d-negative microvascular injury
Alloantibodies are present in
38-70%
of C4d negative glomerulitis cases
Gaston, Transplantation 2010; Loupy AJT 2009
and in
42-100%
of C4d negative glomerulopathy cases
Issa, Transplantation 2008; Sis, AJT 2007; Shimizu Clin Transpl 2009, Haas AJT 2011
C4d negative ABMR – the clinical approach
Renal TX
12/00 – 2/05 (n=691)
Biopsies for cause (n=481)
C4d neg (n=378)
C4d neg + mv lesions
+ serum
(n=28)
C4d pos (n=75)
Regele et al, manuscript in preparation
DSA in C4d-negative vascular injury
Anti-HLA antibodies
P=0.1
Donor specific antibodies
P=0.7
P=0.09
P=0.17
100
100
90
90
80
80
70
70
60
60
50
50
40
40
30
30
20
20
10
10
0
0
Neg Cont
C4d-neg mvi C4d-pos Cont
Neg Cont
C4d-neg mvi C4d-pos Cont
Regele et al, manuscript in preparation
Graft survival in C4d-negative vascular injury
Death censored graft survival
1.0
C4d- (n=378)
0.8
C4d- mvi (n=28)
0.6
C4d+ (n=76)
0.4
0.2
0.0
0
1
2
3
4
5
6
7
8
P<0.0001 (C4d+ vs C4d-)
Regele et al, manuscript in preparation
Summary C4d-negative ABMR
Clinical observations and experimental evidence strongly support the concept of
C4d-negative ABMR
(Micro)vascular injury is a key diagnostic feature that should raise the suspicion
and trigger the search for further evidence of ABMR
Complement independent mechanisms seems to play a much more important role
in chronic ABMR than in acute ABMR
C4d-negative rejection tends to show a rather slow and indolent course
Reliable diagnostic features of C4d-negative ABMR for therpeutic decisions in
individual patients still need to be established