Transcript Transplant immunology and Kidney Transplantation Section of Transplantation Department of Surgery History of Transplantation ►John Hunter (1728-1793)

Transplant immunology
and Kidney Transplantation
Section of Transplantation
Department of Surgery
History of Transplantation
►John
Hunter
(1728-1793)
History of Transplantation
► John
Hunter
►autograft
of
cock’s claw
to its comb
History of Transplantation
►Alexis
Carrel
(1873-1944)
► Collaborator
of
Charles Lindbergh
History of Transplantation
Immunology:
► Peter
Medawar
(1915-1987)
► Nobel Prize1960
History of Transplantation
►Medawar
 together with Billingham published “Use
of skin grafts to distinguish between
monozygotic and dizygotic twins in
cattle”. Heredity 5: 379-397, 1951
 with Billingham and Brent they inoculated
fetuses with cells from prospective donors
“Immunologic Tolerance”
Transplantation
David Hume
► pioneer
in
transplantation
► 1950’s: performed 9
allotransplants into
anterior thigh location
(4/51 - 12/52)
► minimal use of
immunosuppression
Kidney Transplantation
Joseph E. Murray
► Nobel Prize
1990
 Plastic surgeon
with interest in
vascular
surgery
Kidney Transplantation
Kidney Transplantation
►
World’s first
successful
kidney
transplant
involved
identical twin
brothers
(1954); Peter
Bent Brigham
Hospital
Kidney Transplantation
► One
of the
earliest
surviving
kidney
transplants;
identical twin
sisters with
their children
Cadaveric Renal Graft
Renal Vein
Adult Cadaveric Kidney
Renal Artery
Ureter
Living Donor Graft
Living Donor Graft
Living Donor Graft
Living Donor Graft
Living Donor Graft
Extending the Donor Pool
Dual Pediatric en-bloc Graft
Donor Pediatric Aorta
Donor
Pediatric
Renal Arteries
Common
Iliac Artery
Internal &
External
Iliac Artery
Pediatric Renal Transplant
Ureter
Urine
K. Andreoni, MD
Adult Kidney
Varieties of Rejection
Type of
Rejection
Time course
Cause
Hyperacute
Minuteshours
Pre-formed
antibodies
(humoral)
Acute
Days - weeks Cell mediated
(Can be humoral)
Chronic
Months years
Humoral and
cell mediated
► ...
in 1974 he
presented the socalled network
theory, in which he
detailed the complex
system of interactions
whereby the immune
system is activated to
respond to and
counteract disease and
then is shut down
when it is not needed.
► -THEORY ONLY-
Transplant Terminology
► Autograft
(autologous tx)
skin graft for burn
► Isograft
(syngeneic, isogeneic tx)
between genetically identical twins
► Allograft
(allogeneic tx)
cadaveric (deceased donor) renal tx
► Xenograft
(xenogeneic tx) kidney tx
between different species
Specific immune responses to
allograft
► Afferent arm
(incoming signal)
-donor antigens presentation to recipient’s T cells
-T cells activation, proliferation, differentiation
► Efferent
arm (outgoing signal)
-effector leukocytes recruitment
-graft tissue destruction: REJECTION
What type of antigens stimulates
ALLOGRAFT rejection
►Major
Histocompatibility Complex (MHC)
Initiates stronger response compare to miH
► Minor
histocompatibility systems (miH)
this may also be responsible for tissue/organ
rejection however rejection will occur after
several months,
they lack antibody response?
ABO blood groups
►A
Different Story
►NOT MHC antigens
ABO blood groups
► Polysaccharide antigens
on endothelium
► Tx
across natural Ab anti-A/-B blood groups
may result in hyperacute rejection due to
preformed antibody (isoagglutinin Ab)
► Matching
rules as in ‘blood banking’
(universal “0” donors are restricted to “0”
recipients ……..…not always…)
 Depends on isoagglutinin (antibody) titers and
density of antigenic target
Cellular rejection anti-CD3 stain
(T Cells)
Immunosuppression Meds
Mycophenolate mofetil
Rapamycin
Azathioprine
ALG
ATG
Steroid
1960
1970
Tacrolimus
Cyclosporine Daclizumab
OKT3
Basiliximab
1980
1990
2000
Immunosuppression Meds
Rapamycin (Certican)
MNA’s
FTY-720
2000
Anti-CD52 (Campath 1H)
Co-Stimulatory Blockade
Anti-CD40/B7
2010
Immunosuppression
► Steroids
(Prednisone, Solumedrol)
► antiproliferative agents (AZA, MPA)
► polyclonal antibodies (ATG, Thymoglob.)
► calcineurin inhibitors (CsA, Tac)
► monoclonal antibodies (OKT3, anti-IL2R)
► cytokine inhibitor: Sirolimus, Everolimus
► malonitrilamide: Leflunomide, FK778
► Chemokine agonists: ??? FTY-720
► Co-Stimulatory Chronic IS: Belatacept
► Jak3 inhib, other small kinase inh, etc.
Gene map of human chromosome 6
MHC Class I proteins
►Are
expressed on most nucleated
cells on their surface (all tissues)
► Level
of expression is variable (the greatest
in lymphoid cells)
► …are
responsible for activation CD8+ T cells
► ...are
polymorphic…
MHC Class II proteins
► Tissue
distribution is restricted
(present on antigen presenting
cells, some endothelial cells)
► Inflammatory
response (INF) may up
regulate expression of class II proteins
(epithelium, endothelium)
MHC
► The
strength of alloimmunity to MHC
antigens is due to high density of MHC
molecules on tissue cells
 And this density can be upregulated by
inflammatory events…
Methods of Histocompatibility
Matching & Tissue Typing
►Blood
►HLA
group typing (O, A, B, AB)
types of donor and recipient
 Class I and II MHC
►Detection
of anti-HLA Ab (anti-donor
Ab, Donor Specific Ab)
“Special” blood type A
► Type
A1 (~ 85%)
► Type A2 (lower amounts of molecules)
 A2 donors can be used in group 0 & B recipients
if the recipients have low anti-isoagglutinin titers
A2, A2B into B recipients
A2 into 0 recipients
HLA (MHC) typing
resolution method – serological
cytotoxicity assay for evaluation of HLA
phenotype using poly-/monoclonal Ab
► Low
98% accuracy in class I typing
85% accuracy in class II typing (poor)
HLA typing – high resolution
► PCR
► Identifies
single amino acids
sequences (alleles)
Detecting the presence of
anti-HLA Antibodies
Anti-HLA Ab are made following
exposure to blood transfusions,
pregnancy, tissue/organ transplants
(some AI diseases)
Presence of those Ab determines patient’s
risk status (sensitized patient)
anti-HLA Antibodies
► Sensitized
patients require use of sensitive
assay at the time of transplant to ensure the
absence of anti-prospective donor Ab
► High
titer of allo-Ab (anti-HLA) even not
directed against donor predicts earlier, more
severe rejection episodes and requirements
for stronger immunosuppressive regimen
Techniques used for detection of
anti-HLA antibodies
Conventional:
Panel reactive antibodies (PRA) determined
by cytotoxicity in vitro assay against cells
from population. Results are reported as % .
It has some limitation.
Newer methods – uses defined MHC antigens:
-ELISA
-Flow cytometry
Pretransplant Crossmatch
► For
detection of anti-donor Ab to avoid
hyperacute rejection
► To
detect Ab capable of destroying graft
during first post transplant year
► Current
serum and selected sera from the
past are tested in the crossmatch.
Type of crossmatch test used
► NIH
standard cross match technique: C’
Dependent Cytotoxicity (CDC)
 Donor Cells + Recip Serum + C’ = cell lysis
►T
cell and B cell results
► Anti-human globulin-enhanced crossmatch
technique (AHG-CDC) – T cell only
 Allows for more C’ Fixation by AHG X-linking
► Flow
cytometry cross match
 Does not rely on cell lysis, just Ab binding
 Very sensitive, ? Too sensitive
Recip Ab
Donor Ag
Recip Ab
Donor Ag
CDC
May help C’ that
binds weakly to
naturally occurring
Ab by providing Ab
of high avidity and
antigenicity
AHGCDC
Flow Crossmatch
FLOW
CDC
Allograft severe acute rejection
Cells and developmental aspects of the
immune system
►T
cells
► B cells
► NK cells
► All
► Macrophages
► Nonlymphoid
► Dendritic
(APC’s)
are bone marrow
derived
cells
cells
of hematopoietic
origin, initiate
immune response
Nonhematopoietic Cells with
Immune Function
►Endothelial cells
Are capable to support response similar to
professional APC
Express Class I & II MHC, co-stimulatory
molecules, secret proinflammatory cytokines
-Upregulate MHC expression with multiple
stresses: reperfusion injury, infection, rejection
Initiating the response to
foreign antigen
► Antigen
presentation
► Class
I molecules present endogenous
cytosolic antigens (tumor cell toxicity, viral
infection)
► Class
II exogenous antigens
T cell repertoire
► CD4+
have MHC class II restricted TCR
► CD8+
MHC class I
…this means that exogenous antigen (viral particles,
bacteria, parasites, transplanted tissues)
processing depends on CD4+ cells
CD4+ … produce cytokines activate CD8+, cytotoxic
cells, B cells, macrophages
Anatomic sites of antigen encounter
and sensitization
1.
2.
3.
4.
5.
Skin, respiratory tract, intestinal mucosa,
Contact of APCs with antigens
Activation of APC
Migration of APCs to local LN
Effector cells activation: T,B,NK,macrophages
6. Exception is response to alloantigens: ???
presence of large number of passenger donor type
APC that can recruit and activate T cells within the
graft
T cell activation
► Signal
1 TCR/CD3 complex activation
Transduced via cytosolic protein tyrosine
kinase
This is not sufficient to initiate proliferation,
cytokine production
Signal 2 is required
► Lack
of it causes cells anergy, or apoptosis
► Molecules
involved in co-stimulatory second
signal: LFA-1 (CD11a/CD18) and CD2
CD28/B7
CD40/CD154
T cell effector function
► Proliferation
► Differentiation
Cytokines driven processes
Slide 26- Supplemental
Cytotoxic T Lymphocytes CTL
► Require
cell to cell contact
► Perforin
and granzymes (CTLs & NK)
induces cells lysis by perforating cell
membranes
► Fas/Fas
ligand (CD95) is inducing apoptosis
Macrophage activation
► INF
gamma product of T cells activates
macrophages:
enhancing phagocytosis
secretion of proinflammatory agents TNF, IL-1
tissue proteases
nitric oxide
upregulates MHC expression
B cells activation
►B
cell Ag presentation to T-cell (Ig, MHC II)
► Costimulatory signals of T and B cells
interactions
CD40 (on B cell) / CD40 Ligand (on T cell)
B cells transformation into memory cells or
plasma cells
-”B cell rich” acute cellular rejection
Antibodies function
► Fixation
of complement
► Opsonization for phagocytosis
► Opsonization for Antibody dependent cell
toxicity
► Induction of eosinophil degranulation
► We
really have no idea how antibodies
injure most allografts!
Migration and adhesion
► Selectins,
integrins, immunoglobulin
superfamily proteins
► Adhesion
by LFA-1 on lymphocytes
► ICAM-1-2-3 on endothelial cells
► Chemokines
agonists can keep lymphocytes
in lymph nodes and away from grafts!
Immune response to allografts
► Direct
recognition (by Donor APC)
► Indirect recognition (by Recipient APC)
FK506
FKBP12
Calcineurin
Inhibited
Inhibited
both
Kidney Transplantation