Acute cellular and humoral rejection Eva Honsova Institute for
Clinical and Experimental Medicine Prague, Czech Republic
[email protected] Slide 2 1. Cellular theory (Peter Medawar): the
process of graft rejection is immunologically dependent. The cells
(easy to see on histological slides) were recognized and identified
as a cause of tissue damage. Graft rejection: The new era of
transplantation began during World War II. Slide 3 Hyperacute
rejection (HR) The antibodies are not seen in routine histological
staining. HR can occur immediately after transplantation HR was
observed when the kidney was transplanted into a recipient with
pre-existing DSA HR can also be caused by antibodies directed at
allogenic blood groups A and B New generation of laboratory tests
prevents HR thrombosis Slide 4 2. Humoral theory (Paul Terasaki):
evidence that also in later periods after transplantation
antibodies must participate in graft damage. Graft rejection: They
were unable to prove this theory: no tissue marker of confirmation.
Several landmark observations enabled the definition of dg.
criteria of A-MR: P. Halloran: AR with de novo DSAs production and
poor prognosis. H. Feucht: studied complement components and
recognized the relationship of C4d deposition in PTCs in kidney
grafts to graft dysfunction. 2000: 80/70% at 5 years Slide 5
Complement system C4d Positive C4d staining is a marker of
antibody-mediated rejection and represents something like an
imprint that the reaction occurred at the place of positive
staining. Slide 6 Detection of C4d (positive staining in PTCs)
immunofluorescence immunoperoxidase Slide 7 Classification of
rejection changes various centers were developing their own
protocols and their own definitions of the morphological features
without standardization of the nomenclature the communication among
various centers would remain unsatisfactory Banff classification
since 1991 The schema underwent considerable evolution, and was
repeatedly revised and modified in follow-up meetings during a
2-year period Slide 8 Kidney graft biopsy, adequacy criteria A
large number of conditions can affect the allograft, frequently in
combination with varying degrees of arteriosclerosis. the
pre-biopsy clinical diagnosis differed from the definitive
diagnosis in 42% of episodes of graft dysfunction (Pascual et al.
Transplantation 1999;67:737-41) Therapy is changed in 60% following
graft biopsy a) adequacy of the sample; b) processing of the tissue
LMIFEM 2 cores10 gli 2 arteries 3 gli1glus 3 H&E 3 PAS 1-3
Trichrom or Sirius red with elastin IgG, IgA, IgM C3, C4d Fb, ,
light chains, (HLA-DR or others) PU, hematuria, 1 year after Tx
Slide 9 The immunologic threat to the graft begins before
transplantation A. Systemic effects of ischemia/reperfusion injury
I/R up-regulates the expression of HLA antigens by the graft, the
release of a cascade of chemokines, proinflammatory cytokines, and
adhesion molecules. The increased display of HLA antigens
intensifies the immune response. B. Each graft has its medical
history; varying degrees of preexisting, clinically silent injury,
mainly vascular nephrosclerosis No collateral vessel among arteries
and arterioles; stenosis of the lumen represents chronic ischemia
in the interstitial tissue. Slide 10 25% of parenchyma affected, i2
or i3) and foci of moderate tubulitis (t2) IB. Cases with
significant interstitial infiltration (> 25% of parenchyma
affected, i2 or i3) and foci of severe tubulitis (t3) IIA. Cases
with mild to moderate intimal arteritis (v1,25% of the luminal area
(v2) III. Cases with "transmural" arteritis and/or fibrinoid change
and necrosis of medial smooth muscle cells with accompanying
lymphocytic inflammation (v3)"> Acute T-cell-mediated rejection
C: 3. Borderline Changes:"Suspicious" for acute T-cell-mediated r.
C: 4. Acute T-cell-mediated rejection (type/grade) IA. Cases with
significant interstitial infiltration (>25% of parenchyma
affected, i2 or i3) and foci of moderate tubulitis (t2) IB. Cases
with significant interstitial infiltration (> 25% of parenchyma
affected, i2 or i3) and foci of severe tubulitis (t3) IIA. Cases
with mild to moderate intimal arteritis (v1,25% of the luminal area
(v2) III. Cases with "transmural" arteritis and/or fibrinoid change
and necrosis of medial smooth muscle cells with accompanying
lymphocytic inflammation (v3) Slide 11 Acute T-cell-mediated
rejection, tubulitis-schema CD8 recognize peptide antigens
presented by class I MHC, produce IFN Mediate direct cytotoxicity
via granzymes and perforin CD4 recognize peptide antigens presented
by class II, can be divided according to their cytokine production:
Th1: IFN, IL2, TNF, typically in infiltrate of acute rejecting
grafts TH2: IL4,IL5,IL10, provide help for B cells and production
IgE promote eosinophils Inflammatory cytokines produced by T cells
activate epithelial cells, which in turn attract more T cells.
Significant lowering of the rate of episodes of ACR to
approximately 5-10% in the 1st year Grade I: 65-70%, grade II: 30%
Huge progress was made in our understanding of immunological
mechanisms of rejection Slide 12 Acute T-cell-mediated rejection,
type I tubulitis in non-atrophic tubules Banff criteria: IA.
i:>25% of parenchyma affected, i2 or i3 and t2 IB. i> 25% of
parenchyma affected, i2 or i3 and t3 Chapel Hill Standards 1. i 5%
2. Mild to moderate interstitial edema 3. Tubulitis (t1 in 3
tubules in most inflamed area), - scattered eosinophils and ATI are
common - MHC class II in tubular cells - If criteria 1-3 are not
fulfilled, but tubules strongly expressed MHC class II, then an
episode of ACR is suggested Slide 13 tubulitis Slide 14 Acute
T-cell-mediated rejection, type I dg. problems and differential
diagnosis How much inflammation is reactive in subcapsular space
early posttransplant Resolving/partially treated rejection
inflammation in areas of interstitial fibrosis with t1 in the
interface areas 20-65% ATMR show C4d deposits along PTCs: mixed
cellular- and antibody- mediated rejection Differential diagnosis
Drug-induced TIN Difficult or impossible to distinguish from ATMR
Pyelonephritis neutrophlic casts Polyomavirus nephropathy plasma
cells, IH detection Slide 15 Acute T-cell-mediated rejection, type
I Dif. Dg.: polyoma virus nephropathy Slide 16 Acute
T-cell-mediated rejection, type II and III arteritis or
endotheliitis Slide 17 Acute T-cell-mediated rejection, type II and
III differential diagnosis If we strictly follow the Banff
criteria, one lymphocyte is enough for the dg. type II ATMR
rejection. Pre-existing donor disease AS, hypertensionAtheromatous
embolism Severe hypertension Slide 18 Acute B-cell-mediated
rejection /humoral rejection Recognition of AMR requires
demonstration of C4d and circulating antibodies. The diagnostic
criteria of AMR (cases that meet 2 criteria are considered
suspicious for AHR) 1. Neutrophil/lymphocyte margination
(capillaritis), and/or thombosis/necrosis 2. C4d+ in PTCs 3.
Circulating anti-donor antibodies (DSA) Categories: 1.Hyperacute
rejection 2. Acute B-cell-mediated rejection, late acute
B-cell-mediated 3. Accommodation Slide 19 Hyperacute rejection (HR)
Now, HR is not included in Banff schema Complement dependent
recipient with pre- existing DSA Can be C4d negative Differential
dg.: Vascular thrombosis (artery or vein), technical problems or
hypercoagulable state Donor TMA Slide 20 Acute B-cell-mediated
rejection /humoral rejection C4d is the terminal inactive split
product of antibody-activated classical complement cascade and
positive C4d staining represents something like an imprint of the
reaction driven by antibodies. Scoring of C4d staining C4d0
negative 0% of ptcs C4d1 minimal C4d detection 1-10% C4d2 focal C4d
positive 11-50% C4d3 diffuse C4d positive >50% Slide 21 Acute
B-cell-mediated rejection capillaritis: gli, PTCs; thrombosis AHR
has occurred with all IS regiments. The pathology of AHR has a wide
spectrum of findings. However, none of these features is specific.
Slide 22 Acute B-cell-mediated rejection Anti-donor Abs such as
those directed at MHC antigens can trigger AMR. However, the
absence of DSA cannot be taken to exclude AMR. Cases with: C4d+,
DSA+ Cases with: C4d+, DSA- some antigens may be expressed on the
endothelial cells and not on lymphocytes, which are typically used
for the test (MICA). graft can absorb huge amounts of antibodies
from blood and Abs can be below the level of detection. Cases with:
C4d-,DSA+ Negative staining may result from non- complement fixing
antibodies, low reactivity of Abs. Sis B; Halloran P. Endothelial
transcripts uncover a previously unknown phenotype: C4d-negative
antibody-mediated rejection. Current Opinion in Organ
Transplantation. 15(1):42-48, February 2010. Slide 23 Acute
B-cell-mediated rejection Phenomenon of so-called accommodation was
repeatedly described in AB0 incompatible kidney grafts. In this
situation, there are DSA, and C4d positive staining in PTCs. There
is no tissue injury in the graft and the function is stable.
However, in long-term studies, the morphological features of
chronic injury were demonstrated more frequently than in AB0
compatible recipients. cg Slide 24 Rejection remains a central
challenge in the field of transplantation Although huge progress
has been made in our understanding of immunological mechanisms of
rejection there is still a lot unknown. ??? Is humoral response
always pathogenic? What is the role of IgG subclasses in
transplantation? Can some antibodies block these DS antibodies
which bind the complement? Are all DSA harmful? Is there acute
antibody mediated rejection with arterial injury similar to type II
ATMR? (humoral v, in mice it is so) (Hirohashi et al. Am J
Transplant 2010:10;510-517) Slide 25 Now we do not know what
technique will represent a breakthrough and a great improvement in
diagnosis of rejection; gene transcripts or perhaps microRNA, or
something unknown ???
