Transcript Transplantation Immunology
Transplantation
Xiang Li, Urology Department West China Hospital, Sichuan University
Acknowlegement
To Dr. Lu Yiping and Dr. Wang jia To other Colleagues working on renal and liver transplantation
Transplantation is a Dream?
Dream of Paranoia Dream of excellent surgeon who wants to excel himself.
Dream of excellent scientist who believe nothing is impossible.
Can you imagine?
Can you imagine?
Can you imagine?
Contents
Basic concepts of transplantation Clinical Organ transplantation Renal Transplantation, RT Transplantation Immunology MHC and Tissue Matching Graft Rejection Immunosuppression
Definition of Transplantation
Implantation of „non-self” tissue into the body the process of taking cells, tissues, or organs called a graft (transplant) , from one part or individual and placing them into another (usually different individual).
donor : the individual who provides the graft.
recipient or host : the individual who receives the graft.
Blood Transfusion First attempts were unsuccesful (MISMATCH) Discovery of blood groups (Red cell antigens) A-B Landsteiner 1900 Rh Levine, Stetson 1939 Succesful transfusion = Transplantation Others: Bone, Tissue-engineering, etc Transplantation Organ Transplantation
Classification of Renal Transplantation
Auto-RT Cadaveric Allograft RT Living related Living Donor Living unrelated Xenograft RT (In experimental)
Transplantation History
experimental kidney transplantation -1912 Alexis Carel-Nobel prize 1935 human kidney transplant in Russia rejection P.B. Medawar (1945) skin grafts Self skin accepted Relative not accepted ! difference ?
Immunologic mechanism A. Mitchison (1950) What is the Lymphocytes are responsible for rejection
Transplantation History
Peter Gorer (~1935) Identification of 4 group of genes for RBC Gorer and Gorge Snell (~1950) Group II antigens are responsible for rejection Major HistoCompatibility genes (HLA) Nobel prize 1980 George Snell 1954 Succesful kidney transplant between identical twins in Boston – Peter Bent Brigham Hospital Joseph Murray 1991 Nobel prize
HISTORY OF THE RT
1933 First clinical RT (Voronov); 1954 First long-term successful RT(Twin); 1958 Discovery of HLA(Human Lym Antigen); 1959 Radiation be used for immunosupp ression; 1961 Azathioprine (Aza); 1962 Prednisolone; Tissue Matching; 1966 Cross-Matching; Late 1960’ Preservation the Kidney>24hr ;
1972 First successful RT(LRD) in china;
1978 Clinical use of Cyclosporine(CsA).
Key factors for succesful transplantation
Knowledge of MHC haplotypes Effective immunosuppression Ability to identify and treat infections Available donors
Applications of allografting transplantation
The importance of transplantation:
Clinical Organ Transplantation
Liver Transplantation Renal Transplantation
LIVER TRANSPLANTATION
Indication: End stage liver diseases (ESLD) Hepatic Disease to ESLD
Congenital malfomation; Congenital liver metabolic disorders; Acute liver failure; Chronic liver failure: (1) Cirrhosis: Hepatitis B, Alcoholic; (2) Parasites: Hydatid disease of liver, ect.
liver malignance
RENAL TRANSPLANTATION
END STAGE RENAL DISEASES (ESRD) Definition: (1) Various causes; (2) Irreversible injury; (3) Functional failure
.
Morbidity
Europe: 50/million; China: 90-100/million
TREATMENT OF ESRD
DIALYSIS Chronic Ambulatory Peritoneal Dialysis (CAPD); Hemodialysis (HD).
KIDNEY TRANSPLANTATION
Renal Transplantation
Renal transplantation is associated with as survival benefit for patients with ESRD when compared to dialysis; Even marginal donor kidneys confer a significant survival advantage over maintenance dialysis.
The preferred therapy for most of the Pts with ESRD; More cost- effective; Better survival; Better life quality.
CONTRAINDICATION
Active invasive infection; Active malignance; High probability of operative mortality; Unsuitable anatomic situation for technical success; Severe psychological or financial problem.
Pre-OP Selection
ABO Blood Group: Compatible;
Cytotoxicity Test: Donor Lymphocyte Recipient Serum
Cross matching Donor Lymphocyte Recipient Serum Donor Serum Recipient’s Lymphocyte
Mixed Lymphocyte Culture
Tissue typing (HLA)
OPERATION DONOR (1) Living donor
Nephrectomy via flank approach;
Nephrectomy via Laparoscope.
(2) Cadaveric Donor
Total midline incision;
in situ flashing: Euro-collins/UW solution;
Bilateral radical nephrectomy.
Low temperature preservation.
Potential Advantages of living versus cadaveric kidney donor
Better short-term result(about 95% versus 90 % 1-yr function);
Better long-term results(half-life of 12-20 yr versus 8-9 yr);
More consistent early function and easy of management;
Potential Advantages of living versus cadaveric kidney donor
Avoidance of brain death stress;
Minimal incidence of delayed graft function;
Avoidance of long wait for cadaveric transplant;
Potential Advantages of living versus cadaveric kidney donor
Capacity of time transplantation for medical and personal convenience; Immunosuppressive regime may be less aggressive; Help relieve stress on national cadaver donor supply; Emotional gain to donor.
Potential disadvantages of live donation
Psychological stress to donor and family;
Inconvenience and risk of evaluation process(i.e., intravenous contrast);
Operative mortality(about 1 in 2000 Pts.);
Major post operative complications (about 2% of Pts.);
Potential disadvantages of live donation Minor postoperative complications(up to 50% of Pts.); Long-term morbidity(possible mild hyper tention and proteinuria); Risk for traumatic injury to remaining kidney; Risk for unrecognized covert chronic renal disease.
Recipient Operation Extraperitoneally in the contralateral iliac fossa via Gibson incision.
Why contralateral ?
RECIPIENT OPERATION
Blood Vessel Anastomosis:
Donor renal V Recipient’sexternal iliac V Donor renal A Recipient’s internal iliac A
Ureter Anastomosis:
Donor ureter Recipient’s bladder
Anti-reflux anastomosis
Clinical phases of rejection
1.
2.
3.
4.
Hyperacute rejection
(minutes to hours) Preexisting antibodies to donor HLA antigens Complement activation, macrophages
Accelerated rejection Acute rejection
(around 10 days to 30 days) Cellular mechanism (CD4, CD8, NK, Macrophages)
Chronic rejection
(months to years !!) Mixed humoral and cellular mechanism CHRONIC REJECTION IS STILL HARD TO MANAGE !
IMMUNOSUPPRESSION
Immunosuppresents play a very impor tant role in organ transplantation;
Immuosuppresents extremely increase the effect and the survival rate of organ transplantation;
IMMUNOSUPPRESSION
Immunosuppresents are a double edged sword;
the most important thing is to increase their positive effects, and in the same time decrease their side effects (i.e., organ toxicity, infection, tumors, ect.).
Diagnosis of rejection Symptom/Sign
fever; urinary output
;
graft tenderness; graft size
;
hypertension;
myalgia/arthragia.
Laboratory Test Serum creatine, SCr; Urinary creatine, Ucr; Color doppler scan; radiorenogram; Ateriogram; Biopsy: (1) Fine needle aspiration biopsy (FNAB); (2) Core needle biopsy (CNB).
Treatment of kidney rejection
Hyperacute (Sometimes during the operation !) No therapy, usually results in graft failure – kidney should be removed Acute (Most frequently in the first 4 weeks) BIOPSY !
Increase immunosuppression Increase steroid dose Increase cyclosporin (monitor serum level !) ATG, ALG, OKT3 Chronic ACE inhibitors, prostacyclin analog drugs Steroid, Imuran, Cellcept
Transplantation Immunology
Histocompatibility Antigens
Major histocompatibility antigens
MHC class I molecules :
almost all nucleated cells
MHC class II molecules :
APCs, endothelium of renal arteries and glomeruli
Minor histocompatibility antigens :
H Y molecule
Major histocompatibility antigens
Human leukocytic Antigen HLA I.
( α1, α2, α3, β2-microglobulin) Gene-Code alleles: A, B, C loci HLA II.
( α1, α2, β1, β2) Gene-Code alleles: DP, DQ, DR loci HLA III.
Gene-Code alleles: C4A, TNF, HSP70 MHC complex: Gene
Major histocompatibility antigens
MHC loci are highly polymorphic Many alternative alleles at a locus The loci are closely linked to each other A set of alleles is called a HAPLOTYPE One inherites a haplotype from mother and another from father The alleles are codominantly expressed
Inheritance of MHC alleles
Mother Father A/B C/D A/C A/D B/C B/D A/R1 R2/C R2/R1 Possible children of parents with HLA haplotype A/B and C/D R1=C-D recombination R2=A-B recombination
Induction of Immune Responses Against Transplants
alloantigens and xenoantigens : antigens that serve as the targets of rejection the antibodies and T cells that react against these antigens are said to be alloreactive and xenoreactive, respectively. allorecognition direct indirect
Rejection
Senzitization stage Not needed in hyperacute reactions !
Effector stage Alloantibodies: bind to endothelium, activate the complement system, and injure graft blood vessels
Rejection
Effector stage
(Mostly cellular mechanism)
Alloreactive T cells : recruit and activate macrophages ---> DTH response delayed type hypersensitivity Alloreactive CTLs: CTL mediated cytotoxicity lyse graft endothelial and parenchymal cells directly ADCC CD4, CD8 lymphocytes, NK cells, macrophages
Rejection
From: Kuby: IMMUNOLOGY (fourth edition, 2000)
Tissue typing
Microcytotoxicity assay Known antibody to WBCs of donor / recipient Complement mediated lysis if Ab present on cell surface Mixed lymphocyte culture (MLC) Irradiated donor lymphocytes (stimulants) Incubated with recipient lymphocytes 3 H Thymidin incorporatin measured Flow cytometry cross typing DNA analysis Genomic typing (very precise, many subtipes)
Hyperacute Rejection
Occurs within minutes of transplantation Pre-existing IgM (natural) antibodies against ABO blood group antigens less well-characterized xenograft antigens in alloantigen, such as foreign MHC molecules, or alloantigen expressed on vasular endothelial cells
Hyperacute Graft Rejection
Acute Rejection
Occurs within days or weeks after transplantation
Acute vascular rejection
Necrosis of cells of the graft blood vessels (vasculitis) Mediated endothelial by IgG cell complement activation antibodies alloantigens against and
Acute Rejection
Acute cellular rejection
Necrosis of parenchymal cells with lymphocyte and macrophage infiltrates Effector mechanisms :
CTLs
Activated macrophages
Natural killer cells
Acute Cellular Rejection
Chronic Rejection
Occurs over months or years Fibrosis with loss of normal organ structures Wound healing following the cellular necrosis A form of chronic DTH or a response to chronic ischemia caused by injury to blood vessels
Prevention and Treatment of Allograft Rejection
1
Immunosuppression
drugs that inhibit or kill T lymphocytes toxins that kill proliferating T cells antibodies that deplete or inhibit T cells anti-inflammatory agents
Prevention and Treatment of Allograft Rejection
2
Reduce the immunogenicity of allografts
ABO blood group typing HLA typing and matching
induce donor-specific tolerance
blood transfusion
Graft-versus-host Disease (GVHD)
Occurs in bone marrow recipients Initiated by T cell recognition of host alloantigens The effector cells are less well defined : NK cells, CD8 + CTLs, cytokines
Acute GVHD
Epithelial cell necrosis : Skin Liver The gastrointestinal tract Characterized by skin rash, jaundice and diarrhea
Acute GVH
Immunosuppressive therapy 1.
Allogenic transplantation always require immunosuppressive therapy Most of the drugs available are non specific Common side effects of therapy: Infection Cancer Bone-marrow depression
Immunosuppression 2.
Conventional drugs
(1st phase)
Steroids /Prednisone / (0.1-10 mg / kg) Azathioprine /Imuran / (0.5-3 mg/ kg) Cyclophosphamide (0.5-20 mg/ kg) Methotrexate (0.1-0.3 mg/ kg)
Immunosuppression 3.
New drugs (1): CYCLOSPORIN A (=REVOLUTION !) 2-8 mg/ kg FK506 tacrolimus /PROGRAF / Sirolimus - rapamycin Gusperimus - dezoxyspergualin
Effects of cyclosporins
Receptor: cytoplasmic immunophillin calcineurin blockage NF-Atc Rapamycin also binds to immunophillin, but the complex does not block calcineurin, it blocks proliferation in G 1 phase.
Highly lymphocyte specific. IL-2 action is impaired.
T lymphocyte (Th) is blocked.
Immunosuppression 4.
Purin antagonists IMURAN CELLCEPT (micophenolate mofetil ) Mizoribin – bredinin Pirimidin antagonists Sodium-brequinar (highly lymphocyte specific)
Monoclonal antibodies
OKT3 (Anti CD3 mAb) CD3 T cells Anti-TAC (anti-IL2 receptor) Activated T lymphocytes Anti-CD4 Anti-LFA1 + anti-ICAM-1 –
experimental
Anti-cytokine (IL-2, TNF α, IFNγ)
Problems of Transplantation
There are not enough organs At least 150,000 patients in industrially developed countries badly need donor organs and tissues Every 14 minutes another name is added to the national transplant waiting list.
About 16 people die because of the lack of available organs for transplant each day.
Rejection: When the immune system of the host detects foreign graft tissue, it launches an attack, resulting in tissue rejection
Gene technology may as a solution
Gene technology offers the possibility to breed the desired organs in animals.
Lack of organs is no longer a problem Gene technology makes it possible to humanize the bred organs - the immune system identifies the organ as its own tissue.
Immune system rejection is prevented
From which animals are we able to transplant organs
1. The Chimpanzee:
Its DNA sequence differs from ours by only 2%
2. The Baboon:
Its organs are too small for a large adult human
3. The Pig:
Surprisingly similar to our anatomy and physiology
Organ breeding:
•A transgenic animal carries a foreign gene inserted into its genome. •The transgenic animal shows the specific characteristics which are coded on the inserted gene A gene which is responsible for the construction of a human organ makes the organism produce the organ additionally.
The insert of a foreign gene into an animal
I. DNA microinjection The DNA is inserted into the cell with a small syringe II. Retrovirus gene transfer The DNA is carried into a cell by a virus.
Suppression of immune system rejection
The genes which are responsible for the own tissue not being rejected can be injected into an animal embryo the organs of which are then similar to the ones of the human.
It is possible to humanize the bred organs by making certain genetic modifications.
Then the organs are accepted by the immune system.
Conclusion
Transplantation provides us the means of restoring the function of a nonfunctional organ. In the case of BMT it enables us to administer such high doses of chemotherapy that would destroy the BM as well as the residual tumor.
A lot immunologic knowledge had to be collected to understand what is happening.
Conclusion
HLA typing and matching is essential for allografting transplantation.
Effective immunosuppressive therapy (Cyclosporin) revolutionised organ transplantation.
The future is to transplant cells, that would restore the function of the affected organ.
Gene therapy is growing, and will cause another revolution like cyclosporin did in the 1980s.
To seek what everybody has sought To think what nobody has thought Try your best, everything will be possible