Cardiac_transplant_immunosuppression.pptx.ppt

Heart transplant

1. Cardiac transplant
immunosuppression
Dr. Sowmya DNB CTVS

2. Contents
•History
•Immunological basis
•T cells and B cells
•Immunosuppression regimen

3. History
•1905 – first heterotopic heart transplant in dogs.
•1944 – Medawar – during world war II – demonstrated cellular infiltrate
that destroyed the skin transplant from one rabbit to another rabbit.
First demonstrated acute rejection.
•Medawar demonstrated hyperacute rejection. In the same recipient
rabbit if the transplant was done from the same donor rabbit, a second
set of rapid rejection occurred in 5 to 6 days due to pre formed
antibodies – hyperacute rejection.

4. •1950 – Medawar demonstrated that corticosteroids helped prevent
rejection.
•1955 – Merrill and colleagues did first successful kidney transplant in
two identical twins.
•1960 – Lower and Shumway – 1
st
successful experimental cardiac
transplantation.

5. •1964 – Hardy and collegues – first heart transplant in human.
•Recipient was a 68 year old male in shock from end stage ischemic
cardiomyopathy with respiratory failure and amputated gangrene leg

•Donor – Xenograft from a chimpanzee – good contraction on CPB but
the transplanted heart was too small to sustain circulation unassisted
and soon died after CPB was discontinued.

6. •03.12.1967 – first successful human to human heart transplantation by
Christian Barnard in Cape Town, South Africa
•Recipient – Mr Louis Washkansky, 53 years old ex – boxer with end
stage ischemic cardiomyopathy.
•2
nd
heart transplant was done 3 days later in Brooklyn. Recipient was a
18 day old neonate with Ebstein anomaly with refractory heart failure.
Donor was an anencephalic infant. But died after 5 hours due to cardiac
failure and acidosis.

7. •Third heart transplantation – 02.01.1968 by Barnard. Recipient Philip
Blaiberg – 46 year old dental surgeon and refractory heart failure,
severe CAD, large LV aneurysm. He survived for 18 months.
•1968 – around 102 patients had cardiac transplantation.
•1970 – introduced EM biopsy for monitoring allograft rejection.

8. Immunological basis:
•Protein polymorphism: the difference in the three dimensional
structure of the proteins but no change in the function.
•These polymorphic peptides are called as antigens.
•This change in the structure of the proteins helps distinguish self from
non self antigens

9. •There are two types of immune response
•The innate immune response : Immediate and less specific, no
memory.
•The adaptive immune response : delayed response, specific,
memory.

10. •Innate immune cells : white blood cells, NK cells, mast cells, dendritic
cells, Langerhans cells.
•Adaptive immune cells: T cells and B cells

11. •T lymphocytes have specific antigen receptor on their surfaces.
•Each lymphocyte has an antigen receptor specific on its surface that is
specific to one specific antigen.
•This helps in distinguishing self and non self antigen during
immunological development in the thymus. Some lymphocytes are
cross reactive, i.e, bind to more than one antigen.

12. Major histocompatibility complex
•In humans it is called as the Human leukocyte antigen (HLA antigens)
•Chromosome 6 – the difference in sequence of amino acids of the
MHC complex in different individuals.
•Donor MHC molecules will bind to the recipient antigen presenting
cells and activate the T cells which in turn activate the immune
response.

13. •T cell respond only when an antigen peptide is combined in the MHC
peptide binding groove of the antigenic presenting cells.
•MHC protein complex : 3 types
•Class I - A, B, C subtypes : present in all nucleated cells
•Class II – DR, DP, DQ subtypes
•Class III

14. MHC class I and class II molecule

15. •Non self antigens are presented to the T lymphocytes on the grove of
the MHC class I molecules.
•Two types of T cells :
•T helper cells – CD 4 molecules
•Cytotoxic T cells - CD 8 molecules

17. B cells
•B cells have no CD4, CD8.once activated they turn into plasma cells
(that secrete the antibodies) and memory B cells.

18. Cardiac transplantation rejection
•2 ways immune activation
•Indirect activation: The recipient antigen presenting cells bind to the
donor antigens and activate the recipient T cells
•Direct activation : The donor antigen presenting cells carrying the
MHC molecules activate the recipient T cells.

20. Types of rejection
•Cellular rejection: direct and indirect activation – IL – 12, with
targeted cell death by apoptosis.
•Humoral rejection: complement activation and humoral antibodies
(IgG and IgM).

21. Immunosuppression
1)Induction
2) Maintenance therapy
3) Treatment of acute rejection

22. Induction therapy
•Includes two approaches:
1. Basiliximab or Daclizuman – block IL -2 receptors
2. ATG, anti-thymocyte globulin or OKT3 – targets the T cell receptor,
removes it from the surface, or induces cell death by various
mechanisms.

23. Maintenance therapy
•Triple drug regimen
•A) Cyclosporine/tacrolimus: calcineurin blocker, block the production
and release of IL – 2.
•B) Mycophenolate mofetil/ azathioprine/ methotrexate/
cyclophosphamide – anti proliferative.
•C) Adrenocorticosteroids : methylprednisolone/ prednisone – anti
inflammatory effect, inhibit cytokines and macrophage impairment.

24. 1.Cyclosporine and tacrolimus
•Calcineurin inhibition
•Block the production and release of IL – 2
•Inhibits the proliferation of cytotoxic T helper cells.

25. 2.Mycophenolate mofetil, azathioprine, methotrexate, cyclophosphamide
•Anti-proliferative agents
•Interferes with T cell proliferation.
3. Adrenocorticosteroids: methylprednisolone or prednisone
•Anti-inflammatory effect, inhibits transcription of multiple cytokines,
impairs macrophage function and decreases circulating lymphocytes.

26. Individual drugs
Corticosteroids:
Uses:
1. Maintenance therapy
2. Induction therapy
3. Pulse steroid therapy for acute rejection
Mechanism of action:
1.Inhibits IL – 2 production by impairing
transcription.
2.Inhibits leukocyte migration.
3.Reduces adhesion molecule expression and
antigen-presenting cell function.
4.Inhibits lymphocyte proliferation.
Doses:
•Maintenance dose of 20 – 40mg/day, taper to an
alternate dose of 0.1 -0.2 mg/kg/day, and no
steroids by 6 months.
•Acute rejection: 500 – 100mg of IV
methylprednisolone for 3 days (or) oral
prednisone of 2 – 3mg/kg/day for 3 days.
Adverse effects:
•Diabetes, bone disorders, obesity, cushingoid
changes, decreased wound healing, cataracts,
peptic ulcer disease, hypertension.
•4mg of methylprednisolone is equivalent to 5mg
of prednisone.

27. Cyclosporine:
Uses:
Chronic maintenance therapy
•First used in 1979
Mechanism of action:
1.Calcineurin blockade by binding to
cyclophilin.
2.Inhibition of IL – 2
3.Inhibition of T – cell proliferation.
Doses: 25 – 50mg twice daily and increase to
maintain trough levels of 300 – 400ng/ml
Target levels:
post transplant
•0 - 3 months : 250 – 350ng/ml
•3 – 6 months: 200- 300ng/ml
•6-12 months: 150-250ng/ml
•>12 months: 50-150ng/ml
Adverse effects:
Most common is nephrotoxicity, renal arteriolar
vasoconstriction at the preglomerular arterioles.
Chronic - leads to patchy glomerular sclerosis
and interstitial fibrosis, hypertension,
hepatotoxicity, neurotoxicity, renal tubular
necrosis, hyperuricemia, gingival hyperplasia.

28. Tacrolimus:
•first isolated in 1984 from the bacteria
Streptomyces tsukubaensis.
•It is a macrolide compound.
Mechanism of action:
1.Binds to FKBP – 12 protein and blocks
calcineurin.
2.Inhibition of IL – 2
3.Inhibition of T – cell proliferation.
Doses:
1-2mg twice daily.
Target levels:
•post transplant
•0-31 days: 12-16ng/ml
•31-90 days: 10-15ng/ml
•>90 days: 5-12ng/ml
Adverse effects:
• nephrotoxicity, neurotoxicity, glucose
tolerance(more), hyperkalemia,
lymphoproliferative malignancies.

29. Azathioprine:
•Imidazole derivative of 6
mercaptopurine
•Anti-proliferative.
•Maintenance therapy
Mechanism of action:
1.Inhibit purine synthesis and thereby
inhibit lymphocyte proliferation.
Doses:
2 – 2.5mg/kg/day.
Target levels:
No target levels. Dose adjusted to
maintain WBC > 3000/ml.
Adverse effects:
Myelosuppression (leukopenia most
common > thrombocytopenia/anemia)
Concomitant use with
allopurinol(inhibition of xanthine
oxidase) increases myelosuppression. So
reduce dose to 25-33% of pre allopurinol
dose.
Hepatotoxicity, pancreatitis, alopecia.

30. Mycophenolate mofetil
Mechanism of action:
•Mycophenolic acid is the metabolic
compound → inhibits inosine
monophosphate
dehydrogenase→inhibit guanine
synthesis
•Maintenance immunosuppression
Dose
•500mg iv twice daily
Target levels : 1500-1750mg daily
•Trough levels : 2-5ng/ml.
•Adverse effects:
•nausea, vomiting, abdominal pain,
diarrhoea, loss of appetite,GI
bleeding, jaundice, pancreatitis,
leucopenia and myelosuppression.

31. Cyclophosphamide
•Alkylating agent derived from nitrogen
mustard.
•Maintenance immunosuppression
Mechanism of action:
•Interferes with DNA replication by alkylating
and cross linking DNA strands.
•Has greater toxicity on B cells than T cells.
Dose :
•1 - 1.5 mg/kg/day.
Target levels:
•Titrate to maintain the WBC levels of 3000
Adverse effects:
• Bone marrow suppression with maximal
effect at 7 -10 days.
•Hemorraghic cystitis, alopecia, GI distress,
interstitial pneumonitis.

32. Methotrexate:
•Analog of folic acid
•Maintenance immunosuppression
Mechanism of action:
•Competitively inhibits dihydrofolate reductase
enzyme → inhibits purine synthesis.
•Anti proliferative effects on lymphocyte and
other rapidly dividing cell lines.
Dose:
•1 -5 mg BD/ TDS for 3 doses per week for 3 to
12 weeks
Target levels:
no target levels
•Monitor leukocyte count.
Adverse effects:
•Bone marrow suppression resulting in
leukopenia, anemia and thrombocytopenia.
•Hepatotoxicity, nephrotoxocicty, stomatitis
and hypersensitivity pneumonitis.

33. Sirolimus:
•Derived from actinomycete Streptomyces
hygroscopicus.
•Discovered in 1965.
•It is a macrolide antibiotic
Mechanism of Action:
•It is target of rapamycin (TOR) inhibitors.
•TOR is a cytoplasmic enzyme that helps in
converting signals from the T – cell surface to
the cell nucleus for stimulation of growth and
proliferation of lymphocytes.
•It inhibits cell proliferation stimulated by
growth factors.
•The net effect is selective blockade of cytokine
signal mediated cell division and proliferation
with arrest of the cell cycle in the G1 phase.
•It acts synergistically with cyclosporine and
tacrolimus.
•Can be substituted for either cyclosporine or
tacrolimus in case of renal dysfunction
Dose : 2 – 5 mg/day
•Target levels : 5 – 15 ng/ml.
Adverse effects:
•Hypercholesteremia, elevated triglycerides,
thrombocytopenia, interference with wound
healing.

34. Anti thymocyte globulin
•Polyclonal antilymphocyte preparation
containing variable amounts of specific
antibodies directed against T – cell molecules.
•Antibodies with activity directed against HLA
class I and class II antigens.
Mechanism of action:
•Polyclonal anti – T cell antibody preparation
that blocks surface receptors impairs
effectiveness of antigen presenting cells,
destroys T lymphocytes.
•Impairs the effectiveness of antigen
presenting cells.
Dose:
•Rabbit ATG(thymoglobulin) – 5mg of which
>90% is rabbit gamma immunoglobulin.
•The standard dose of 1.5mg/kg/day is infused
through a central venous catheter over 4 to 6
hours.
Adverse effects:
•Thrombocytopenia, arthralgia, edema, fever,
chills, anaphylactic reaction, respiratory
distress, serum sickness.

35. Monoclonal antibodies
•Specificity against certain cell surface
receptors.
•OKT3 (Anti – CD 3) The binding of a antigen to
the T cell receptor (antigen MHC complex)
activates the CD – 3 complex that transmits an
intracellular signal that initiates T cell
activation.
•They deplete the CD 3 complex within a few
hours (30 – 60 minutes).
•But the antibody levels start to rise within 1
week of discontinuing the therapy.
•But this immediate rise in antibodies is not
observed when polyclonal antibodies are used.
•So primarily used as induction therapy or in
treating acute or refractory rejection.
•Dose : 2.5 – 5 mg IV daily for 7 – 14 days.
Monitoring:
•A target suppression of CD – 3 cells to an
absolute cell count of < 10cells/ml and less
than 5 % of total lymphocytes.
Adverse effects:
•cytokine release syndrome - fever, chills,
headache, nausea, myalgia, mild hypertension,
bronchospasm and profound hypotension.
•Production of antimurine antibodies.
•Increased susceptibility to CMV, infection,
lymphoproliferative disorders with repeated
prolonged administration.

36. Anti CD25 (Basiliximab, daclizumab)
•Humanized IgG monoclonal antibodies.
•Anti rejection prophylaxis in induction
therapy.
Mechanism of action:
•Monoclonal anti CD 25 antibody against the IL
– 2 receptor on T lymphocytes.
•They bind to the alpha chain of the IL – 2
receptor on activated T lymphocytes.
Dose:
•Basiliximab 20mg iv following completion of
bypass. A repeat dose of 20mg IV on post op
day 4.
•Daclizumab: administer 1mg/kg IV within 24
hours before transplantation and every 14
days for 4 doses
Monitoring: none is used clinically.
Adverse effects: none reported so far.

37. Plasmapheresis
•Plasmapheresis involves removing blood from the patient, separating plasma by
centrifugation or membrane filtration and reconstituting the remaining blood to the
original volume with fresh plasma or 5 % albumin.
•It is a passive process.
•Removes antibodies, IL – 1, IL – 6, TNF - alpha and anaphylotoxin C3a.
•Can be used in hemodynamically compromising rejection.
•TECHNIQUE: A large bore indwelling catheter into the internal jugular
vein/femoral/subclavian vein.
•To maintain fibrinogen level above 100mg/dl.
•Performed for 3 successive days.
•When anti donor antibodies are detected plasmapheresis can be done at weekly
intervals till the anti donor antibodies.

39. Immunoadsorption
•Active process in which the immunoglobulins pass through filtration
membranes.
•Specific antibodies are removed using columns containing
immunoadsorbents that specifically bind to immunoglobulins.
•Used in the presence of recipient anti – HLA class I antibodies against
the donor heart.
•Improved EF and decrease in PRA following acute vascular rejection.

40. Photopheresis
•Immunomodulatory therapy based on leukopheresis.
•It involves drawing blood, separating the whole blood configuration and returning
the red cells and plasma to the patient.
•The leukocytes are treated with 8 – methoxypsoralen, a photosensitizing agent
and exposed to UVA light in the photoactivation chamber.
•The treated leukocytes are returned to the patient.
•The photoactivation process induces cross linking of the DNA. It induces
apoptosis of the leukocytes. They are phagocytosed by the dendritic cells.
•Extracorporeal photopheresis alters the composition of recipient T lymphocytes
toward a greater preponderance of T regulatory cells, which promote down
regulation of graft infiltrating T cells.

42. Total lymphoid irradiation.
•It is a low dose radiotherapy that targets lymphoid tissues including the cervical,
axillary, mediastinal, peri aortic, iliofemoral lymph nodes, thymus and spleen.
•B cells and T cells are susceptible to radiation therapy.
•Initial depression in lymphocyte counts recovers in 3 – 4 months.
•TLI dosage involves three separate fields that provide radiation to all major
lymphoid bearing areas.
•Total dose of 800cGy using twice weekly doses of 80cGy each.
•Common toxicity includes leukopenia, thrombocytopenia.
•Rare complication is acute megakaryocytic leukemia.

43. Rejection
•Target cells within the heart include myocytes and endothelial cells of coronary
vasculature.
•The presentation of donor antigens to the appropriate recipient T cells leads to T cell
activation and clonal proliferation. It causes up regulation of T cells.
•Activated T cells generate and release cytokines induces proliferation of immune cells
and recruitment of macrophages.
•These events in release of powerful biological effectors of myocyte injury and necrosis.
•This is prevented by immune suppression.
•Balance between immune suppression and their toxicity, infection and malignancies are
to be considered.
•Rejection process occurs in “waves” of heightened immunological activity within the
allograft.
•Infections and stress are considered to be the inciting agent.

44. Pathology of allograft rejection
•Studied by doing serial endomyocardial biopsy.
•International society of heart and lung transplantation (ISHLT) classify
the rejection grades.
•The rejection grades are based mainly on amount of inflammatory
infiltrate and presence of myocyte damage.

45. •Histological categories of acute rejection are
•Cellular
•Humoral
•Hyperacute

46. Cellular rejection
•It is a mononuclear inflammatory response – lymphocytic, directed
against the cardiac allograft.
•Sampling of the right ventricular septum should be there.
•Presence of myocyte injury warrants augmentation of
immunosuppression.

48. Humoral rejection.
•Antibody directed against donor antigens located on the endothelial surface of
the allograft coronary microvasculature.
•The inflammatory process with neutrophils and macrophages involves the vessel
wall.
•The hallmarks of microvascular rejection involves endothelial cell activation,
increased vascular permeability, microvascular thrombosis and myocardial cell
degeneration.
•Immunofluorescence studies on the endomyocardial biopsy identifies fibrinogen,
IgG, IgM and complement components. Immunofluorescence criteria for acute
humoral rejection is given below .

50. Hyperacute rejection
•Immunological attack of the preformed antibodies against HLA
epitopes in the donor heart.
•Can be due to anti endothelial antibodies.
•Activation of complement cascade produces severe endothelial cell
damage, platelet activation, initiation of clotting cascadeand
microvascular thrombosis.
•Occurs within minutes of re perfusing the heart.

51. Identifying a rejection
•Echo: decrease in the systolic function can be observed in acute
rejection.
•Endomyocardial biopsy is the gold standard
•A rejection episode is a clinical event that is characterized by an
abnormal myocardial biopsy and augmentation in the patient’s
immunosuppression.
•Recurrent rejection can lead to graft dysfunction and hemodynamic
compromise, increased risk of allograft vasculopathy.

52. High-risk form of rejection
•Grade 3B or 4 rejection on biopsy.
•Vasculitis and evidence of humoral rejection on biopsy.
•Rejection with hemodynamic compromise.
•Acute rejection in the presence of circulating antibodies.
•Hemodynamic compromise with low cardiac output, decreased EF requiring
inotropic support should be promptly treated. They have increased risk of
mortality in the subsequent 2 years.

53. Investigation
•Endomyocardial biopsy every week for the first 4 to 6 weeks and
gradually reduced to every 3 to 4 months.
•Subtle symptoms include fever, joint pain. Immediate endomyocardial
biopsy and institution of appropriate therapy is needed.

54. Treatment of acute rejection
•Outpatient / inpatient treatment depending on clinical judgement.
•Oral prednisosne 100mg for 5 days and taper by 10mg/ day until
previous maintenance dose is reached.
•IV methylprednisolone 1g/day for 3 days followed by prednisolone
100mg for 2 days and taper by 10mg/day until maintenance dose is
reached.
•Unresponsive : ATG for 5 – 7 days, azathioprine to mycophenolate
mofetil, cyclosporine to tacrolimus, plasmapheresis, photopheresis and
total lymphoid irradiation.

55. •Endomyocardial biopsy – mild rejection – then the rejection episode is
resolved.
•Frequent biopsies in the next three months.

57. Thank you