Post on 16-Jul-2015
Overview
• Definition in transplantation
• Adaptive immune responses to allografts
• Graft rejection
• Hematopoietic Stem Cell Transplantation
Overview of Hematopoietic Stem
Cell Transplantation
• Sources of HSCT
• Donor selection and manipulation
of the graft
• Complications of HSCT
– Graft rejection
– Graft-versus-host disease
• HSCT for The Treatment of Primary
Immunodeficiency Disorders
Transplantation
• Treatment for replacement of non-functioning
organs and tissues with healthy organs or
tissues
• Increasing during the past 45 years
• Hematopoietic stem cells, kidneys, livers, and
hearts
Abbas AK, et al. Cellular and molecular immunology Ed 8th
Transplantation
• Graft: cells, tissues, or organs
• Donor: provides the graft
• Recipient, host: who receives the graft
• Orthotopic transplantation; normal anatomic
location
• Heterotopic transplantation: different site
Abbas AK, et al. Cellular and molecular immunology Ed 8th
Transplantation
• Autologous graft: to the same individual
• Syngeneic graft: two genetically identical
individuals
• Allogeneic graft, allograft: between two
genetically different individuals of the same
species
• Xenogeneic graft , xenograft: different species
Abbas AK, et al. Cellular and molecular immunology Ed 8th
Adaptive immune responses
to Allografts
• Ag that stimulate adaptive immune responses
against allografts are histocompatibility
proteins
• Strong rejection reactions; major
histocompatibility complex (MHC) molecules
• Weak or slower rejection reactions; minor
histocompatibility antigens
Abbas AK, et al. Cellular and molecular immunology Ed 8th
Adaptive immune responses to Allografts
• Allogeneic MHC molecules of a graft can be
presented for recognition by the recipient’s T
cells in 2 different ways; the direct and indirect
pathways
• Direct allorecognition can generate both
CD4+ and CD8+ T cells that recognize graft
antigens and contribute to rejection
Abbas AK, et al. Cellular and molecular immunology Ed 8th
Graft rejection
• Classified on the basis of histopathologic
features and the time course of rejection
after transplantation
Abbas AK, et al. Cellular and molecular immunology Ed 8th
Rich RR, et al. Clinical Immunology principles and practice. Ed 3rd
Hyperacute Rejection
• Thrombotic occlusion of the graft vasculature
• Within minutes to hours after host blood vessels are anastomosed to graft vessels
• Mediated by preexisting antibodies in the host circulation that bind to donor endothelial antigens
Acute Rejection
• Injury to the graft parenchyma and blood vessels mediated by alloreactive T cells and antibodies
• Several days to a few weeks
• Immunosuppression
Abbas AK, et al. Cellular and molecular immunology Ed 8th
Chronic Rejection and Graft
Vasculopathy
• In the kidney and heart: vascular occlusion and
interstitial fibrosis
• Lung transplants: thickened small airways (called
bronchiolitis obliterans)
• Liver transplants: fibrotic and non-functional bile ducts
Abbas AK, et al. Cellular and molecular immunology Ed 8th
Prevention and Treatment of
Allograft Rejection
• Minimize alloantigenic differences between
the donor and recipient
• ABO blood typing: avoid hyperacute rejection
• HLA alleles
– HLA-A, HLA-B, and HLA-DR
– Zero-antigen mismatches predict the best
survival
Abbas AK, et al. Cellular and molecular immunology Ed 8th
Hematopoietic Stem Cell Transplantation
• HLA discovery in 1968
• Human stem cell transplantation (HSCT)
provide treatment for a variety of
congenital and acquired disorders; SCID
in 1968
Rich RR, et al. Clinical Immunology principles and practice. Ed 3rd
Sources of hematopoietic stem cells for transplantation
Rich RR, et al. Clinical Immunology principles and practice. Ed 3rd
Bone marrow stem cells
• Multiple aspirations along the iliac crests under general anesthesia
• 500 mL- 1 L depended on the type of transplant and on the weight of the recipient
• HLA-identical transplantation – injected intravenously without further manipulation
into a central line in the recipient
• Mismatched transplantation – T-cell depleted and injected intravenously
Rich RR, et al. Clinical Immunology principles and practice. Ed 3rd
Peripheral blood stem cells • G-CSF to the donor, 10 μg/kg/day x 5 days
• Purified by positive selection, enumerated and
injected
Cord blood • Collected in heparinized medium and stored in
liquid nitrogen, and small aliquots are preserved
for HLA typing
• Thawed and injected into the recipient without
further manipulation
Rich RR, et al. Clinical Immunology principles and practice. Ed 3rd
HSCT from a related HLA-identical donor
• Best for rapid engraftment and immune
reconstitution
• The mature T cells contained in the graft provide
a first line of immune reconstitution after
transplant
• Rapid increase circulating T lymphocytes 2
weeks after HSCT
Rich RR, et al. Clinical Immunology principles and practice. Ed 3rd
HSCT from a haploidentical donor
• No such donor is available
• based on the ability of donor-derived stem cells
to repopulate the recipient’s vestigial thymus
and give rise to fully mature T lymphocytes
• life-saving procedure of SCID infants
Rich RR, et al. Clinical Immunology principles and practice. Ed 3rd
T-cell depletion
• Soybean lectin: agglutination of mature marrow cells and
removed by sedimentation
• E-rosetting (with sheep erythrocytes) and density
gradient centrifugation
• Incubation of the marrow with monoclonal
antibodies to T lymphocytes plus complement; Campath-1G, Leu 1
• Positive selection of CD34+ cells using monoclonal
antibody affinity
Rich RR, et al. Clinical Immunology principles and practice. Ed 3rd
HSCT from matched unrelated donors
• Increasingly used to treat severe primary
immunodeficiencies
• Bone Marrow Donors Worldwide (BMDW)
registry
• 3–4 months to identify a MUD
• Preparative chemotherapy regimen in the
recipient (even in the case of SCID) and graft
versus-host prophylaxis
Rich RR, et al. Clinical Immunology principles and practice. Ed 3rd
HSCT using unmanipulated cord blood
• Lower risk of GvHD than with MUD
• Based on the urgency of the transplant, the cell
dose required, and the number of HLA
disparities
• Requires pre-transplant conditioning and GvHD
prophylaxis, irrespective of the underlying
disease
Rich RR, et al. Clinical Immunology principles and practice. Ed 3rd
Sources of hematopoietic stem cells for transplantation
Rich RR, et al. Clinical Immunology principles and practice. Ed 3rd
Complications of hematopoietic
stem cell transplantation
• Conditioning regimen toxicity
– affect several organs e.g. busulfan-lung
damage, veno-occlusive disease
– anemia, thrombocytopenia, and leukopenia
• Graft rejection
• Graft-versus-host disease
• Infections
Rich RR, et al. Clinical Immunology principles and practice. Ed 3rd
Graft rejection
• Immunocompetent cells in the host specifically recognize and react to donor-derived stem cells
– the degree of immunocompetence of the host
– the degree of HLA disparity
– the number of stem cells infused
– the type of conditioning regimen used
– the possible pre-sensitization of the host to donor histocompatibility antigens
Abbas AK, et al. Cellular and molecular immunology Ed 8th
Rich RR, et al. Clinical Immunology principles and practice. Ed 3rd
Graft rejection
• SCID, graft rejection unlikely because of
the profound immunodeficiency
• Regimen: busulfan + cyclophosphamide,
± antithymocyte globulin (ATG)
• Phagocytic or hemophagocytic cell
disorders, a more aggressive conditioning
regimen
Rich RR, et al. Clinical Immunology principles and practice. Ed 3rd
Acute graft-versus-host disease
• Donor-derived T lymphocytes to the recipient’s
antigens
• Early as 1 week after HSCT
• Potentially fatal
• The major risk factors for aGvHD include
– HLA mismatch
– Older age of the recipient
– Gender mismatch
– Prior herpes virus infection
Abbas AK, et al. Cellular and molecular immunology Ed 8th
Rich RR, et al. Clinical Immunology principles and practice. Ed 3rd
Acute GvHD
• Highgrade fever, MP rash (confluent),
exfoliative dermatitis, diarrhea, and liver
abnormalities (hepatomegaly, ↑elevated
liver enzymes, jaundice), protein-losing
enteropathy, abdominal pain
• Third space loss
• Bone marrow aplasia, high susceptibility to
infections
Abbas AK, et al. Cellular and molecular immunology Ed 8th
Rich RR, et al. Clinical Immunology principles and practice. Ed 3rd
Chronic GvHD
• Symptoms persist or appear after 100 days
• Skin changes (scleroderma-like lesions,
hyperpigmentation, hyperkeratosis, skin atrophy,
ulcerations), tissue fibrosis, limitation of joint
motility
• Fibrosis of exocrine glands (sicca syndrome),
fibrosis of lungs and liver, immune dysregulation
and autoimmunity
Rich RR, et al. Clinical Immunology principles and practice. Ed 3rd
Chronic GvHD
• Acute GvHD represents a major risk factor for
cGvHD
• Older age of the recipient
• Transplantation from a multiparous female donor
into a male recipient
• Minor histocompatibility incompatibility
Rich RR, et al. Clinical Immunology principles and practice. Ed 3rd
Prevention of GvHD
• Fully matched donor
• T-cell depleted HLA-mismatched donor
• Pharmacological GvHD prophylaxis
– Cyclosporine A daily for 6 months,
or methotrexate (15 mg/m2 on the first day, and then
10 mg/m2 at day 3, 6
– or combination
– ATG
Rich RR, et al. Clinical Immunology principles and practice. Ed 3rd
Treatment of GvHD
• Immunosuppressive drugs
• Steroids, ATG, mycophenolate mofetil, cyclosporine A, monoclonal antibodies directed to HLA (anti-CD3) or to Th1-type cytokines (anti-TNF-α) and cytokine receptors (anti-CD25, daclizumab)
• Topical steroids and calcineurin inhibitors may alleviate mucosal and skin symptoms
• Ursodeoxycholic acid may be useful in cGvHD with significant liver involvement
Rich RR, et al. Clinical Immunology principles and practice. Ed 3rd
Infections
• Adenovirus, CMV, EBV, parainfluenzae III
virus. PCP, aspergillus, bacterial infection
• Viral infection after HSCT may cause
interstitial pneumonia, enteritis, and
encephalitis
• EBV cause B-cell lymphoproliferative
disease (BLPD)
Rich RR, et al. Clinical Immunology principles and practice. Ed 3rd
HSCT for SCID
• Immune suppression is not required
• No conditioning regimen is necessary in related
HLA-identical donor
• US centers adopt same policy for T cell-depleted
mismatched HSCT
• European centers tend to use conditioning
regimens prior to mismatched or MUD HSCT,
particularly in SCID with residual autologous NK
Survival following HSCT for SCID
• Related HLA-identical, MUD, and T cell-depleted
haploidentical HSCT were 100%, 94%, and 52%,
respectively
• Has improved over the years
Rich RR, et al. Clinical Immunology principles and practice. Ed 3rd
Factors influence survival
• Younger age at transplantation leads to superior
survival
– Among 38 infants who were treated by Buckley and
collaborators before 3.5 months of age, 37 (97%)
have survived
• Co-trimoxazole prophylaxis for recipients
• Absence of pre-transplant pulmonary infection
among recipients
• Type of SCID
Rich RR, et al. Clinical Immunology principles and practice. Ed 3rd
Factors influence survival
• Survival following related HLA-mismatched
HSCT is better in infants with B+ SCID than with
B− SCID (64% vs 36%, respectively)
• The poorer outcome in infants with B− SCID
may reflect the presence of autologous NK cells
detectable in most of these infants
Rich RR, et al. Clinical Immunology principles and practice. Ed 3rd
Complications following HSCT for SCID
• 56% of all deaths were due to infections,
25% to GvHD, and 5% to BLPD (B-cell
lymphoproliferative disease)
• Immune dysregulation and autoimmunity
Rich RR, et al. Clinical Immunology principles and practice. Ed 3rd
Quality and kinetics of T-cell
immune reconstitution
• The effectiveness of HSCT in SCID: the
normalization of the number and function of T
lymphocytes
• Reconstitution differs substantially depending on the
type of transplantation
• The kinetics of T-cell reconstitution influenced by the
recipient’s age
• Early transplantation (<3.5 months of age) leads to
superior thymic output
Rich RR, et al. Clinical Immunology principles and practice. Ed 3rd
Quality and kinetics of T-cell immune reconstitution
Related HLA-identical donor
• The unmanipulated graft contains mature T lymphocytes
• expanded in 2 weeks
• Oligoclonal, have a memory (CD45R0) phenotype
• Fully competent, and provide the recipient with functional immunity
MUD
• Present mature T cells
• Conditioning regimen
partly impairs immune
development
• Naive (CD45RA+ CD31+)
T lymphocytes appear in
3–4 months
• Number tends to peak 1
year after HSCT
Rich RR, et al. Clinical Immunology principles and practice. Ed 3rd
Quality and kinetics of T-cell immune reconstitution
Rich RR, et al. Clinical Immunology principles and practice. Ed 3rd
• T-cell receptor excision circles (TRECs); extrachromosomal DNA
episomes generated during V(D)J recombination
• not duplicated during mitosis
• identify newly generated naive T lymphocytes
Rich RR, et al. Clinical Immunology principles and practice. Ed 3rd
Quality and kinetics of T-cell immune reconstitution
• Quantification of TRECs
• assess engraftment of bona fide stem cells and
to monitor the persistence of immunity
• Decline by 10 years
• Possible that the SCID thymus is not able to
sustain active thymopoiesis for as long as a
normal thymus
Rich RR, et al. Clinical Immunology principles and practice. Ed 3rd
Reconstitution of B- and NK-cell immunity
• ≥2 years to develop the engraftment of B cells
for SCID
• 6 of12 recipients of HLA-identical bone marrow,
and 21 of 76 patients treated by unconditioned T
cell-depleted haploidentical transplant had
evidence of donor-derived B lymphocytes
• 62 of 102 survivors were requiring intravenous
immunoglobulins
Buckley RH. Annu Rev Immunol 2004
Reconstitution of B- and NK-cell immunity
• Depend on the nature of the genetic defect
• B+ SCID, IL7RA gene defect usually develop
normal B-cell immunity after HSCT even if no
donor-derived B cells are present
• γc or JAK3 deficiency (both of which
compromise B-cell function) often remain
dependent on immunoglobulin substitution
• More limited data are available about
reconstitution of NK cell function
Rich RR, et al. Clinical Immunology principles and practice. Ed 3rd
HSCT for immunodeficiencies
other than SCID
• Residual T cell-mediated immunity
• pre-transplant conditioning regimen is
required, even HLA-identical donor
• Alternative donors (MUDs and cord blood)
• Medical emergency
• Clinical history and quality of life
Rich RR, et al. Clinical Immunology principles and practice. Ed 3rd
Survival following HSCT
• 23/79 HLA-identical transplant
• 13/79 by T cell-depleted haploidentical HSCT
• 43/79 by MUD HSCT
• The survival rates: 78.5%, 53.8%, 78.1% Rich RR, et al. Clinical Immunology principles and practice. Ed 3rd
HSCT for immunodeficiencies other than SCID
HLA-identical Haploidentical MUD
Omenn’s syn 75% 41% 50%
MHC class II def 54% 32% -
WAS 87% 52% 71%
FHL 71% - 70%
Cartilage-hair
hypoplasia
Over all 50%
Purine nucleoside
phophorylate
Overall 50%
CD40L def Overall 46% at 25 yr of age
Wiskott–Aldrich syndrome
• Early as 1968, with partial success
• Full correction following HSCT first in 1978
• Good outcome in HLA-identical HSCT
• MUD HSCT was effective especially <5 years
• Cord blood transplantation increasingly
Cytotoxicity defects
• Familial hemophagocytic lymphohistiocytosis (FHL)
– a stable donor chimerism ≥20% is sufficient to provide
long-term remission
– genetic testing is strongly recommended before HSCT
from a sibling is attempted
• Chediak–Higashi syndrome
– Better results with HSCT from HLA-identical siblings or
MUDs
– 3 patients, all are alive and in full remission