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Transplantation Immunology - Download as PowerPoint

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									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
MHC and Tissue Matching Graft Rejection Immunosuppression



Transplantation Immunology
  

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 Donor Living related





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 !  What is the difference ?   Immunologic mechanism A. Mitchison (1950)  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 1954 1958 1959

     

First clinical RT (Voronov); First long-term successful RT(Twin); Discovery of HLA(Human Lym Antigen); Radiation be used for immunosuppression; 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 Recipient Serum
Cross matching





Donor Lymphocyte 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 hypertention 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 Donor renal A

Recipient’sexternal iliac V Recipient’s internal iliac A





Ureter Anastomosis:
 

Donor ureter

Recipient’s bladder

Anti-reflux anastomosis

Clinical phases of rejection
1.

Hyperacute rejection (minutes to hours)
 

Preexisting antibodies to donor HLA antigens Complement activation, macrophages

2.

3.

Accelerated rejection Acute rejection (around 10 days to 30 days)


Cellular mechanism (CD4, CD8, NK, Macrophages) Mixed humoral and cellular mechanism
CHRONIC REJECTION IS STILL HARD TO MANAGE !

4.

Chronic rejection (months to years !!)



IMMUNOSUPPRESSION


Immunosuppresents play a very important 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 :
cells

almost all nucleated

MHC class II molecules :
of renal arteries and glomeruli

APCs, endothelium



Minor histocompatibility antigens :
Y molecule

H-

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 Gene-Code alleles: C4A, TNF, HSP70



HLA III.




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  3H 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 antigens in xenograft  alloantigen, such as foreign MHC molecules, or alloantigen expressed on vasular endothelial cells

Hyperacute Graft Rejection

Acute Rejection


Occurs within transplantation


days

or

weeks

after



Acute vascular rejection
Necrosis of cells of the graft blood vessels (vasculitis)
Mediated by IgG antibodies against endothelial cell alloantigens and complement activation



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 Rejection1


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 Rejection2


Reduce the immunogenicity of allografts
 

ABO blood group typing HLA typing and matching blood transfusion



induce donor-specific tolerance


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 nonspecific 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 G1 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 Activated T lymphocytes

 


Anti-TAC (anti-IL2 receptor)




Anti-CD4 Anti-LFA1 + anti-ICAM-1 – experimental Anti-cytokine (IL-2, TNFα, 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. When the immune system of the host detects foreign graft tissue, it launches an attack, resulting in tissue rejection



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


								
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