Renal: 1:00 - 2:00
Wednesday, 20, 2009
Dr. George
Abbreviated Terms: Tx = Transplant
I.
II.
III.
IV.
V.
VI.
VII.
Immunologic Basis of Graft Rejection
Scribe: Hunter Neill
Proof: Taylor Nelson
Page 1 of 5
Introduction [S1]: Inquiry
a. This is going to be an immunology lecture about implantation
i. Implications of dental and optometry practice
b. Picture shows an article
c. Dr. Edward Jenner reasoned that milkmaids tended not to get small pox because they were exposed to cow
pox. He proposed taking small scraping from those that have had small pox and immunize someone with it by
scratching it into their skin.
Peter Medawar [S2]
a. Considered the father of transplantation
b. He discovered that transplantation rejection had an immunologic basis
c. What does implantation rejection mean exactly?
i. Swapping of body parts from one individual to another
ii. Refer to letter f
d. Many of the people that have kidney failure must go on dialysis (not the greatest solution) – another option is to
give them a new kidney
e. Transplants mainly used for end stage organ failure
i. End stage renal failure
ii. End stage heart failure (though less common)
f. What happens if you take a tissue and move it from one individual to another (someplace other than the eye)
i. It attacks it – the body rejects it
ii. This is a uniform observation throughout history
g. He observed that a woman with extensive burns on her torso that were so extensive the treatment was difficult
i. Normally they would take a pinch graft to help cover up the area
1. They would pinch a piece of skin between the skin and forefinger from a non-burned area and whack
the top off with a scalpel and eventually it would grow out and cover the area
ii. She was so burned that her brother donated the rest of the skin
1. The woman rejected the brothers skin more quickly than her own
2. Also observed that it rejected more quickly the second time they put it on than the first time (few days
sooner)
h. Conclusion: This is because of an immune response. By this point immune reactions had been defined with
specific reaction
i. Among those is upon second exposure to an antigen that you will respond more quickly
ii. This is the basis of immunity – this is the reason why we don’t get sick from illnesses twice
Immunologic Basis of Graft Rejection [S3]
a. He noticed that immunity with these three characteristics:
i. Inducibility – it wasn’t there before but it is now
ii. Memory – the second time you respond more quickly
iii. Specificity – that you can distinguish between different things
iv. This is the basis of transplantation
b. Medawar published a massive paper in the 1940s – one of the most important works in immunology and
certainly transplantation biology
First Set Rejection [S4]
a. He took a couple of rabbits (Blue and Red Rabbits) and did a transplant of skin from one to another
b. Notice that just like the person who was burned – it was rejected in 7-8 days
Autograft acceptance [S5]
a. Histological view
b. When you put the graft in, the graft will revascularization and heal
c. A few neutrophils and other cells that are infiltrating the area go away and it completely resolve
d. Timing of this can vary from animal to animal and species to species but about the same
Second Set Rejection (Memory) [S6]
a. He took another skin from blue rabbit and again placed it on the red rabbit (previously received a blue rabbit
transplant)
b. Upon second exposure to the graft the rejection happened more quickly
c. Conclusion: This is evidence of immunological memory
d. This is the evidence of immunological memory
First-set rejection [S7]
a. Instead of revascularization followed by a mild cellular infiltrate and then healing in
Renal: 1:00 - 2:00
Scribe: Hunter Neill
Wednesday, 20, 2009
Proof: Taylor Nelson
Dr. George
Immunologic Basis of Graft Rejection
Page 2 of 5
b. He saw a monster cellular infiltrate consisting of a large number of inflammatory cells, neutrophils, lymphocytes,
etc.
c. Eventually thrombosis and necrosis of the graft (the graft just fell off)
VIII. Specificity [S8]
a. Here are two genetically distinct animals of the same species
b. Clearly the individual that had received the graft could tell it was being exposed to a graft from the same
individual
c. What if it (red rabbit) got exposed to a graft from a different individual? And what if you do it at the same time?
i. The blue rabbit give a primary graft shown by the stripped dot
ii. Then it gets another graft from the blue rabbit – rejected in 3-4 days (evidence of memory)
1. Quicker
2. Stronger
3. Longer Lasting response
iii. At the same time, take another graft from a third party (yellow rabbit – no genetic relationship with either
the blue or red) and place it on the red rabbit (even in close proximity)
1. The blue graft rejects 3-4 days
2. The yellow graft rejects 7-8 days just like the primary graft
iv. This animal can distinguish between the first donor (blue) and the other donor (yellow)
d. This, by definition, is specificity – this is evidence of memory
e. This was the key observation that transplantation is a rejection phenomena
IX. Second-set rejection [S9]
a. When we look at the histological graft showing memory, the graft doesn’t even get revascularized
b. Instead we see a massive cellular infiltrate and the graft is destroyed – get necrotic tissue
X. Terminology [S10]
a. Autograft – One site to another on the same individual (“Auto” means self)
i. Done in the laboratory as a control
b. Isograft – Between two genetically identical individuals
i. If the rabbit has a twin
ii. Or in the case of inbred mice
XI. Terminology (cont.) [S11]
a. Allograft – between genetically distinct individuals of the same species
i. HE REPEATED THIS
ii. Performed routinely in humans
b. Xenograft – between two different species (“Xeno” – meaning really other)
i. Duckbill platypus to a rabbit or vice versa
XII. Beginning of Rejection [S12]
a. In the center is a mouse and the white is a gloved hand
b. In the center is the beginning of a rejection on a mouse
i. A small amount of scabbing like tissue is showing up on top of the graft
ii. It has since revascularized but has started to reject
iii. Seeing that massive infiltrate
c. Eventually the graft will fall off completely and eventually the wound will close up
XIII. Rejected Mouse Skin Graft [S13]
a. How does it work?
b. It an immunological phenomena – memory, inducibility, and specificity
c. It’s a function of the genetic relatedness between donor and recipient – REPEATED
XIV.
Rejection is mediated by T cells [S14]
a. T-Cells or thymus derived cells actually mediate this response
b. Illustration shows that rejection is mediated by T-cells
i. On the far left the mouse (strain B) is given a graft from strain A (wait 14 days)
ii. The graft is rejected and become necrosis and scabby
c. What cells are mediating this response? If transferring cells than you would transfer the response
d. Took this animal and took the spleen out and purified the T-cells and transferred it to a completely separate
mouse that had never been transplanted before
i. Then they gave it the same transplant that the first mouse had
ii. By transferring the T-cells you were able to transfer the memory
1. The mouse showed second set kinetics or a memory response – the graft was rejected more quickly
even though it had never seen the graft before
Renal: 1:00 - 2:00
Scribe: Hunter Neill
Wednesday, 20, 2009
Proof: Taylor Nelson
Dr. George
Immunologic Basis of Graft Rejection
Page 3 of 5
2. Instead all the mouse got was T-cells and that transferred the memory of the exposure to the graft –
hints that rejection that rejection is mediated by T-cells
iii. The mouse one the top right is the control mouse
XV. Role of CD4 and CD8 Cells [S15]
a. What types of T-cells mediate this response – CD4 and CD8
b. CD4 is characteristic of helper T-cells – MHC antigens when the recognize them
c. CD8 are associated with cytolytic type (killing) responses
d. The best way to tell if CD4 cells are responsible for the response is to get rid of the cells
i. Can inject the animal with anti- CD4 monoclonal antibodies – this leaves only the CD8+ cells
ii. What happened in the presence of only CD8+
e. The chart is a survival plot – percent survival (y) and time after the transplant (x)
i. Each stair step represents rejection by one or more animals
f. When you eliminate CD4 cells you prolong graft survival
g. If you eliminate all the CD8 cells leaving the CD4 cells, they will reject at the same speed
h. CD4 cells are necessary and sufficient for graft rejection - REPEATED
i. In contrast, when you leave just CD8 cells, they do eventually reject
j. CD8 cell participate in graft rejection – clearly help the response but are not necessary
k. If you eliminate them both than you get very long graft survival
i. Even if you eliminate them both – rejection will eventually happen because the cells come back
XVI.
Laws of Transplantation [S16]
a. The immune response is directed toward something. Why are all the previously mentioned associated with
rejection? Is there a gene that controls it? Research was done to find the genetic locus.
b. Tx between individuals of the same inbred strain will succeed
i. Inbred strains are experimental strains (mice) bred repetitively between brother and sister
1. P 1 X P2  F1 X F1  F2 X F2
2. And then continue doing brother sister mating
3. You will eventually have animals that are nearly genetically identical – like identical twins
ii. Very similar to an autograft
c. Tx between inbred strain are rejected – individuals that are not genetically similar will reject their grafts
d. Tx parent to F1 will succeed, but the reverse will fail
i. Transplant from the parent to the child will succeed but the reverse will not
XVII. Mating of inbred mouse strains with different MHC haplotypes [S17]
a. Rejection is controlled by a genetic locus – known as MHC
b. Major Histocompatability Complex (MHC) this is a cluster of genes that has no recessive genes - they are all
dominant (or Co-Dominant)
c. This validates the law (transplants from the parent to the progeny will succeed)
d. The whole basis is self verses non-self recognition
i. MHC is the major factor
ii. You are receiving a gene from each parent – the F1 mouse has a B gene and a K gene so a Tx from either
parent will succeed
iii. A transplant from the F1 to the Parent will result in the parent recognizing the other gene (b/b parent
recognizing the k or the k/k parent recognizing the b gene) – resulting in rejection
e. Transplant rejection is governed by the MHC – the inheritance pattern of those genes govern who’s going to
reject and who isn’t
f. The whole reason for sexual reproduction is to generate diversity by inheriting commonitorial combinations from
different individuals the basis of transplant rejections
XVIII. The Human MHC [S18]
a. Just for fun – picture of an MHC – not expected to know
b. Different genes within the complex that are typed for during clinical transplantation
i. Class 2 and Class 1
ii. Tissue distribution are quite different – Class 1 is found in every cell whereas class 2 are found on cells that
present antigens primarily dendritic and macrophages
iii. The genetic basis of transplant rejection has to do with the MHC – and the inheritance pattern controls who
rejects and who doesn’t
XIX.
Picture (a) [S19] – Tissue Typing
a. The more genetically identical and individual is the better off they are in terms of keeping their transplant
b. If they are genetically different they will reject their transplant
c. Classical method for tissue typing
d. To see how close a donor and recipients genetic relatedness is to one another
Renal: 1:00 - 2:00
Scribe: Hunter Neill
Wednesday, 20, 2009
Proof: Taylor Nelson
Dr. George
Immunologic Basis of Graft Rejection
Page 4 of 5
i. Take the donor cell and use antibodies that are specific for HLA antigens
ii. Antibodies are specific and directed at certain proteins – in this case you can use them as probes to see
which MHC antigens are on the surfaces of these cells
iii. Can use blood or lymph node cells
iv. A2 is a specific antibody that binds to a specific locus of the MHC
v. If you have antibodies against that and there are antigens on the cell – the antibodies will bind to the
surface and fix complement that will punch holes in the cell. Then you can look to see if the cell dies or not.
If the antigens aren’t there then the antigens wont bind and their wont be death
vi. Can use wells in the lab. If the cells all die the antigen is there and if they don’t die the antigen is not there
vii. This can help you determine what alleles and individual has in their MHC
XX. Picture (b) [S20]
a. If you have a kidney recipient that is A1 and A7 and two different donors
i. Donor 1 – A1 and A7
ii. Donor 2 – A2 and A3
b. You would choice the Donor one based on the better match – Donor 1
XXI.
Mixed Leukocyte Reaction [S21]
a. Skipped
XXII. Acute Rejection [S22]
a. Primary Cellular – you can transfer the propensity to reject a graft by transferring cells from one individual to
another
b. Massive infiltration of macrophages and lymphocytes
c. Decreased graft function
d. Clinically appears at >10 days post-tx and can occur anytime thereafter
XXIII. Acute Rejection – Grade 1a [S23]
a. The histological section is an H&E stain depicting the graft infiltrating cells of a heart transplant
b. The darker areas are nuclei of transplant cells
c. When you transplant a heart from one to another you must look for graft rejection
d. With the kidney you can look for rejection using creatinine clearance
e. Heart transplant patients you don’t have that test
i. If you wait till functional problems manifest - the recipient tends to die
ii. To prevent this a catheter is used to take a biopsy and look at the infiltrate
f. This is a mild grade of rejection - you can see macrophages and lymphocytes
i. This would probably not be treated
XXIV. Acute Rejection – Grade 3a [S24]
a. This is a much ore sever case of eosinophils
b. Massive disruption of the muscle tissue – infiltration of eosinophils as well (pink/ orange cell)
c. If allowed to continue the recipient would likely die
XXV. Chronic Rejection [S25]
a. Probably the most vexing problem from a clinical standpoint
b. Slow and steady decline of graft function and progressive occlusion of vessels/passageways
c. Result of cellular and humoral mechanism – we don’t really know how it works
XXVI. Chronic Rejection (Pictures) [S26] – mouse model
a. The inner black layer is the intima
b. With chronic rejection the intima starts to proliferate – it will continue to do so until the vessel is totally occluded
i. In the heart progressive occlusion of the coronary artery will occur until the heart wont work any more
ii. Results in the death of the organ
1. Kidney – need another transplant
2. Heart – may cause death
XXVII. Hyperacute Rejection [S26]
a. First observed in transplant patient with a blood type mismatch
b. Causes by the presence of preformed antibodies against the donor – REPEATED
i. Blood typing antigens
c. The preformed Ab will flood into the graft and immediately bind to the capillary endothelium and fix complement
d. The compliment will blow holes in the endothelial wall and cause chemotaxis and attract neutrophils
e. Massive clotting in the vessels occurs due to the endothelial lining
i. Will end up with blockage of capillaries leakage of the vessels
ii. Can watch it happen (fast)
Renal: 1:00 - 2:00
Scribe: Hunter Neill
Wednesday, 20, 2009
Proof: Taylor Nelson
Dr. George
Immunologic Basis of Graft Rejection
Page 5 of 5
XXVIII. NOTE: Dr. George stated that the information pasted the slides containing infiltration of neoplastic tissue
in the liver would not be tested and have therefore been excluded from the transcript. Many of the slides in
the remainder of the lecture were skipped.
[End 44:30 min]