From the Departments of Immunology (P.I.H., P.D.M., R.B., R.I.L.) and
Cardiothoracic Surgery (P.I.H.), Royal Postgraduate Medical School,
Hammersmith Hospital, London, UK, and the Department of Cardiothoracic
Surgery, Harefield Hospital (M.H.Y., M.L.R.), Middlesex, UK.
Correspondence to Philip Hornick, Department of Cardiothoracic Surgery, Royal Postgraduate Medical School, DuCane Rd, Hammersmith Hospital, London W12 ONN, UK.
Methods and Results—Alloreactive helper (HTLf) and cytotoxic
(CTLf) T cells were enumerated by use of limiting dilution
analysis. These assay systems were refined to make them
specific for the direct pathway of allorecognition and more sensitive
in the case of the HTLf assay. Recipient:anti-donor frequencies were
generated in 10 long-term recipients of heart grafts with progressive
chronic rejection and compared with those against equivalently HLA
mismatched recipient:third-party controls. For HTLf, direct pathway
donor-specific hyporesponsiveness was detected in 5 of the 10
recipients (HTLf <1:100 000). Of these 5 recipients, 4 also had low
anti-donor CTLf (<1:100 000). In the 5th recipient, although the CTLf
was >1:100 000, it was significantly lower than that estimated
against the third-party control.
Conclusions—Donor-specific hyporesponsiveness is demonstrated in
50% of recipients in both the HTLf and CTLf compartments of the direct
alloresponse. Direct allorecognition therefore appears unlikely to be
responsible for the progression of chronic rejection, implicating
indirect allorecognition as the predominant immunological driving
force. Furthermore, these data have potential implications for graft
outcome, adjustment of immunosuppression, and recipient monitoring.
Chronic rejection of the cardiac allograft is manifest by the
development of TxCAD.1 Its morphological
characteristics differ from conventional coronary artery
disease, although in its most advanced form it may resemble
conventional nontransplant coronary artery
disease.2 Despite improvements in early survival,
the major cause of late death in recipients of cardiac allografts is
TxCAD, accounting for 40% of all deaths or retransplantations that
occur within 5 years of transplantation.3 The
process is limited exclusively to the allograft, including venous
structures, and its progression may be very rapid compared with
conventional atheroma.2 4 5 6 7
Both alloantigen-dependent and -independent events appear to influence
this condition (reviewed in References 8 and 98 9 ). However, tangible
experimental evidence for an immune basis is indicated by data derived
from small animal models of TxCAD,10 11 12 as well
as an observed correlation with anti-endothelial
antibodies and anti-HLA antibodies produced by the
recipient.13 14 15 16 Immunological factors may well
act in concert with antigen-independent processes, including
traditional risk factors for atherogenesis. The relative contribution
of nonimmune risk factors is controversial and depends on the series
analyzed.4 5 6 17 18 19
Given that there is strong evidence implicating immunological
mechanisms in this long-term rejection
process,10 11 12 effective strategies to induce
donor-specific tolerance should extend the lifespan of allografts.
Two pathways contribute to allorecognition of HLA-mismatched tissues
(reviewed in References 20 through 2220 21 22 ). The "direct" alloresponse
involves recognition of intact donor HLA antigens on the surface of
donor cells by recipient T lymphocytes. Donor, bone marrow–derived
APCs that are transplanted with the graft play a major role in
triggering recipient T cells with direct anti-donor allospecificity.
The strength of this response is accounted for by the uniquely high
precursor frequency of T cells with specificity for allogeneic MHC
molecules. Its vigor that appears to violate the rules of self–MHC
restriction is driven primarily by antigenic
mimicry.23 24 Direct helper and cytotoxic T cell
recipient: anti-donor HTLf/CTLf frequencies are on the order of
1:103 to
104 and always
<1:105 for four to six HLA antigen mismatched
donor and recipient pairs.25 26 On the basis of
the results of experimental models of transplantation, this pathway is
most active during the first few weeks after grafting but becomes less
potent once the donor-derived APCs have left the
graft.27 28 Indeed, in the rodent, once the donor
APCs are eliminated, the graft appears to lose its immunogenicity in
several strain combinations and is not
rejected.29 30 Furthermore, the
presentation of donor alloantigens by the parenchymal cells
of the graft appears to favor the induction of donor-specific
tolerance.31 The second pathway, the
"indirect" alloresponse, involves the presentation of
donor alloantigens that are shed from the cells of the graft by
recipient APCs to recipient T cells. This requires the internalization
and processing of the alloantigens that are then recognized in peptidic
form bound to recipient HLA class II molecules. This is the same means
by which T cells recognize conventional protein antigens. It has been
argued that this pathway contributes to later, more chronic forms of
rejection.27 Although firm evidence for such a
role in the context of chronic rejection is still lacking in human
transplant recipients, its importance in graft rejection has been
demonstrated in rodent models32 33 and recently
in humans demonstrating acute cardiac allograft
rejection34
The purpose of this study was to determine whether donor-specific
tolerance could be detected in T cells with direct anti-donor
allospecificity in human heart transplant recipients after prolonged
graft residence. Recipients with evidence of progressive TxCAD were
selected. The recipient:anti-donor response was quantified by use of
an improved technique of limiting dilution analysis which
specifically estimates frequencies of recipient helper (HTLf) and
cytotoxic (CTLf) T cells with direct allospecificity for donor
cells.
HLA Typing
HTLf and CTLf Limiting Dilution Assays
We further refined these assay systems to make them specific for the
direct pathway of allorecognition and more sensitive in the case of the
HTLf assay by eliminating the confounding effects of extraneous IL-2
production: Specificity for the direct pathway of
allorecognition was achieved by depletion of APCs from the responder
cell population, thus removing any possibility of self-restricted
alloantigen (indirect) presentation. Previous reports using
non–APC-depleted responder cells cannot negate and have not accounted
for a contribution to the estimated frequency by self-restricted
alloantigen recognition.
The key to maximizing sensitivity and specificity of the HTLf assay is
to eliminate extraneous sources of IL-2 production so that the
only stimulus to IL-2 release is the direct anti-donor alloresponse of
the IL-2–producing T cells in the recipient. We identified three
sources of extraneous IL-2 production. Autologous mixed
lymphocyte reactions may occur within the responder population and
within the irradiated stimulator population. "Back
presentation" by responder APCs to T helper cells
resident within the donor population provides an additional potential
source of extraneous IL-2. Such "extraneous" IL-2
production may thus alter the estimation HTLf. Our solution has
been to use monoclonal antibodies to deplete the responder population
of antigen presenting cells and the stimulator population of
CD4+ and CD8+ T cells.
These cellular interactions no longer occur, and unwanted IL-2
production is markedly reduced. These modifications have led to
significant differences in T helper cell frequencies compared with the
results obtained with unseparated responder and stimulator cell
populations. Such maneuvers are clearly essential in the detection of
donor-specific tolerance.41
Preparation of Responder and Stimulator Cells
Preparation of Stimulator Spleen Cells
Culture Medium for HTLf Assays
Antibody-Mediated Depletion
Responder Cells
Flow Cytometry
Maintenance of the IL-2–Dependent Indicator Cell
Line, CTLL-2
HTLf Assay
CTLf Assay
Control wells for the calculation of background activity consisted of
24 wells containing irradiated stimulator cells alone. Wells were
classified positive for IL-2 production or cytotoxic activity,
if 3H-TdR incorporation or
51Cr release exceeded the mean plus 3 SD of these
control wells, respectively. Other control wells for both HTLf and CTLf
contained responder cells in medium alone (negative control).
Statistical Analysis
Study Design
In all recipients, both CTLf and HTLf were measured against stored
donor cells and against a third party population of cryopreserved
spleen cells. These data are presented in graphical form in
Figs 1
In this context, three specific points merit discussion. First,
donor-specific direct pathway T-cell hyporesponsiveness occurs in the
context of clinical cardiac transplantation in a substantial proportion
of recipients. Furthermore, this hyporesponsiveness occurred in both
the CTLf and HTLf compartments of the recipient anti-donor T cell
repertoire. Although related observations have been
made,46 47 48 49 no previous studies have reported
specific direct pathway hyporesponsiveness in both HTLf and CTLf
demonstrated by limiting dilution analysis and using donor
material.
These experiments do not reveal the mechanism for this tolerance.
Induction of anergy or deletion are both potential mechanisms. The
mechanisms of this allograft-induced hyporesponsiveness are therefore
not clear, although suppression would seem unlikely in that limiting
dilution analysis plots in which the number of seeded responder
cells is plotted in a semilogarithmic fashion against the fraction of
nonresponding cultures always yielded straight lines, confirming
single-hit kinetics. We consider that they are likely to reflect the
consequence of alloantigen recognition on the surface of donor cells
that are incapable of providing the molecular interactions that T cells
need to become fully activated.31 On the
basis of experimental models of transplantation, it was first proposed
that the activation of CD4+ and
CD8+ T cells requires the
simultaneous receipt, of two distinct
signals.50 The first signal results from the
ligation of the T-cell antigen receptor. It has become clear in recent
years that the second signal is provided by key "costimulatory"
molecules, such as B7.1 (CD80) and B7.2 (CD86), that are selectively
expressed by specialized, bone marrow–derived
APCs.51 52 53 More importantly, the receipt of
signal 1 owing to cognate recognition of antigen in the absence of
signal 2 is not a neutral event but leads to the T cell being rendered
refractory to further stimulation (anergy).54 It
is well known that the inflammatory response that commonly accompanies
allografing leads to the induction of HLA class II molecule expression
by a variety of tissue cells, including endothelial
cells and fibroblasts in the heart and epithelial cells in the kidney.
However, these cells lack expression of key costimulatory molecules and
may therefore lead to the induction of nonresponsiveness in
allospecific T cells.
The second point is that the progression of chronic rejection, as
manifested by TxCAD, is unlikely to be mediated by or dependent on a
persistently high frequency of T cells with direct anti-donor
allospecificity. All the recipients included in this study had clear
evidence of progressive TxCAD. There were no detectable differences in
terms of the number of prior acute rejection episodes, donor
ischemic time, donor:recipient HLA mismatch, and
cytomegalovirus status, which might conceivably contribute to
hyporesponsiveness, compared with the rest of the study group. Not only
did the recipients have TxCAD, but the time of onset of disease (within
1 year of transplantation) was no different from that of the recipients
with no evidence of hyporesponsiveness. The detection of
hyporesponsiveness in recipient T cells with direct anti-donor
allospecificity in the face of progressive TxCAD indicates that the
direct pathway alloresponse is not responsible.
The final point that merits discussion is an inference, namely that
strategies designed to promote tolerance induction in transplant
recipients will need to take into account T cells with indirect
allospecificity. It is clear from these data that chronic rejection can
still proceed despite profound alloreactive hyporesponsiveness in
direct pathway T cells. While the relative contribution of antigen- and
non–antigen-dependent factors in the progression of chronic rejection
remains unclear, perhaps the most plausible explanation for its
inexorable progression is that it continues to be driven by T cells
with indirect allospecificity20 32 33 with some
contribution from non–antigen-dependent risk factors, eg, lipids,
according to the model of Ross.55 If this is the
case, this response will be continually stimulated by a continual
supply of specialized recipient APCs. Furthermore the graft itself will
be unable to promote tolerance to itself in the way that it can for T
cells with direct allospecificity. Based on these considerations, the
induction of tolerance in T cells with indirect allospecificity remains
one of the outstanding challenges in the biology of
allotransplantation.
One of the unresolved questions that arises from these data is why
donor-specific hyporesponsiveness occurred in some, but not in other,
recipients. There are several possible ways to account for these data;
however, the explanation that we favor is that the residual T cells
with direct anti-donor specificity in recipients with long-standing
allografts are those of low affinity and that the high-affinity clones
have been rendered nonresponsive in all recipients.
These data provide encouragement that direct pathway donor-specific
tolerance is achievable in clinical transplantation without the need
for specific tolerizing protocols. We additionally demonstrate, in
contrast to other investigators,46 48 that the
attainment of donor-specific hyporeactivity is not necessarily
associated with stable graft function, as evidenced by the angiographic
progression of TxCAD.
Objective and quantifiable evidence of a diminution in T cells with
direct alloreactivity may have relevance for the reduction of
immunosuppresive regimens; however, until the activity and
immunosuppressive susceptibility of indirect alloreactive mechanisms
have been assessed in the context of chronic rejection, such a
reduction would seem potentially perilous. These data offer the
challenge of devising strategies to inhibit the more persistent,
indirect pathway of allo-sensitization.
Received July 18, 1997;
revision received November 25, 1997;
accepted December 1, 1997.
© 1998 American Heart Association, Inc.
Clinical Investigation and Reports
Assessment of the Contribution That Direct Allorecognition Makes to the Progression of Chronic Cardiac Transplant Rejection in Humans
Abstract
Top
Abstract
Introduction
Methods
Results
Discussion
References
Background—Two populations of T
cells contribute to allograft rejection. T cells with direct
allospecificity are activated after recognition of intact MHC
alloantigens displayed at the surface of donor passenger leukocytes
carried within the graft. In contrast, T cells with indirect
allospecificity recognize donor alloantigens as processed peptides
associated with self (recipient)–MHC class II molecules. In small
animal models of transplantation, direct pathway T cells dominate the
acute rejection process and are rendered tolerant to the graft after
the loss of donor passenger leukocytes. It has been argued that
indirect pathway T cells contribute substantially to continual graft
damage after passenger cell loss. The purpose of this study was to
determine whether donor-specific tolerance could be detected in T cells
with direct anti-donor allospecificity in human heart transplant
recipients after prolonged graft residence.
Key Words: transplantation • immunology • rejection • immune system • lymphocytes
Introduction
Top
Abstract
Introduction
Methods
Results
Discussion
References
Donor-specific
immunological tolerance is the most desirable, although elusive, goal
in clinical transplantation for two main reasons. The first is that
protracted immunosuppressive treatment is associated with an increased
susceptibility to both opportunistic infections and malignancy. The
establishment of immunological tolerance to an allograft would obviate
the need for their use. The second reason is that despite the
impressive improvement in graft survival in the first year after
transplantation, the attrition rate of organ allografts after the first
year has not changed significantly over the past 2 decades because of
the inexorable course of chronic rejection.
Methods
Top
Abstract
Introduction
Methods
Results
Discussion
References
Recipients
Ten heart transplant recipients (patients A through J) receiving
maintenance cyclosporine and azathioprine
immunosuppression were investigated, all of whom had developed chronic
TxCAD in their first posttransplant year. The length of graft residence
at the time of alloreactive T-cell frequency estimation varied from 1
to 7 years. Chronic rejection was diagnosed by use of standardized
angiographic criteria.5 Its progression was
demonstrated from the time of these studies in all recipients by
angiography performed on at least one additional occasion. No
recipients received donor bone marrow or donor-specific transfusions.
No recipients were diabetic or hypertensive, and none had any evidence
of previous cytomegalovirus infection (clinical evidence and detection
of early antigen fluorescent foci by the Deaff test). For all
recipients, posttransplant hyperlipidemia was treated
and corrected.
All recipients and donors were typed by use of conventional
serological methods,35 36 and from April 1993,
HLA-DR typing was performed by polymerase chain reaction amplification
with sequence-specific primers.37 38
Methods to estimate HTLf and CTLf have been previously
described.39 40 The stimulator cells were derived
from donor splenic tissue that was cryopreserved at the time of the
organ harvest; the responder T cells were prepared from recipient's
PBMCs.
Preparation of Recipient (Responder) PBMCs
Peripheral blood was obtained from heart graft
recipients. Mononuclear cells were isolated by density gradient
centrifugation on Lymphoprep 1.077 g/mL (Nycomed Pharma
AS). After extensive washing, responder cells
(107 cells per 1 mL) were resuspended in a
freezing mixture comprising serum from AB donors and 30% dimethyl
sulfoxide (Analar BDK). AB serum was added at 1:3 volumes to a give a
final concentration of 7.5% dimethyl sulfoxide and 75% AB serum.
Samples were subsequently stored in liquid nitrogen until required.
Portions of spleen were obtained during organ retrieval.
Single-cell suspensions were released by injecting cold sterile RPMI
into the splenic material with a syringe; mononuclear cells were then
enriched on Lymphoprep gradients and cryopreserved as above.
The assay culture medium for all HTLf assays consisted of RPMI
1640, supplemented with sodium bicarbonate (0.24% final
concentration), L-glutamine (2 mmol/L), penicillin (50
IU/mL), streptomycin (50 µg/mL), sodium pyruvate (1 mmol/L) (all
from Flow Laboratories), and 5% AB serum.
Stimulator Cells
Cryopreserved spleen cells were thawed rapidly and washed twice
in RPMI 1640. CD4+ and CD8+
T lymphocyte depletion was carried out with
anti–CD4+- and
anti–CD8+-coated immunomagnetic beads
(Dynabeads, Dynal AS). Immunomagnetic beads are at a concentration of
1.4x108/mL. Beads were added to spleen cells at
a ratio of 2:1, assuming that 70% of the stimulator cell population
were CD4+ and that 30% of the stimulator cell
population were CD8+. Immunomagnetic cell
separations were performed at 4°C. Stimulator cells were gently mixed
for 45 to 60 minutes. A magnet was then applied to the outside wall of
the test tube to collect the bound cells and free beads as per the
manufacturer's instructions. The stimulator cell suspension was then
subjected to a further two rounds of depletion, this time at a ratio of
1:1.
Cryopreserved responder cells were thawed rapidly and washed
twice in RPMI 1640. Adherent cells were removed from PBMCs by
incubation for 1 hour at 37°C on tissue culture–grade Petri dishes
(Greiner). PBMCs were incubated on ice for 30 minutes with an antibody
cocktail consisting of mouse anti-human monoclonal antibodies against
HLA-DR, CD14, CD19, CD56, CD16, and CD33 (Becton Dickinson). The cells
were then washed with cold RPMI and incubated with goat anti-mouse
antibody microbeads (Miltenyl Biotec GmbH). Depletion was achieved by
running the cell suspension and microbeads through a MiniMacs
separation column applied to a magnet (Miltenyl Biotec GmbH). Eluted
cells were then used for subsequent experiments.
To determine the efficiency of depletion, cells were stained
with directly conjugated anti-CD3-FITC and anti-DR-PE antibodies
(Simultest, Becton Dickinson) and then washed and fixed with 1%
paraformaldehyde in PBS. Cells were subsequently
analyzed by use of an EXCEL flow cytometer (Coulter
Electronics). In all experiments, T cell–depleted stimulators
contained 
4% CD3+ cells, and HLA class
II–depleted responders contained 1% DR+
cells.
The continued proliferation of the murine cytotoxic T
lymphoblastic line CTLL-2 (European Collection of Animal Cell Cultures,
Salisbury, UK) is dependent on the presence of human or murine IL-2 or
murine IL-4.42 43 The CTLL-2 cells do not
proliferate in response to human (unlike mouse) IL-4. The fact that the
mouse IL-4 receptor does not bind human IL-4 was also reported by
Mosmann et al,43 and we have confirmed this using
CTLL-2 cells. The line was maintained in culture medium with the
addition of human recombinant IL-2 (10 U/mL, Boehringer) and
10% FCS. The cells were cultured in 25-cm2
flasks (Costar) and were subcultured every 3 days. Before use in a
limiting dilution assay, the CTLL-2 cells were washed twice and
cultured overnight in normal culture medium but without recombinant
IL-2. We added 1x103 cells to all wells of each
assay.
The design of the HTLf assay was as described
previously.39 After the depletion processes
outlined above, the stimulator and responder cells were resuspended in
RPMI with 5% AB serum. Graded numbers
(0.03125x104, 0.0625x104,
0.125x104, 0.25x104,
0.5x104, 1x104,
2x104, 3x104,
4x104, and 5x104) of
responder cells in 50 µL were added to 24 replicate wells of U-bottom
96-well microtiter plates (Flow Laboratories). In some cases, fewer
responder dilutions were used because of a limitation in stimulator
(donor) material. Stimulator cells were gamma-irradiated with 35Gy by
use of a 137cesium source (Gammacell 1000, Atomic
Energy of Canada Ltd), and 5x104 cells were
added in 100 µL to each of the wells. Plates were incubated at 37°C
in 5% CO2 and 95% air for 72 hours. After
incubation, the plates were gamma-irradiated with 25Gy (8-MeV linear
accelerator, Philips MEL). The presence or absence of IL-2
production in each well was assessed by adding
1x103 CTLL-2 cells in 25 µL of medium. Adding
the IL-2–responsive cells directly to the wells has been shown to be
more sensitive than adding the IL-2–responsive cells to previously
removed supernatant.44 Eight hours later, 1 µCi
of tritiated thymidine (3H-TdR) (Amersham
International plc) in 25 µL of medium was added to each well. After a
further 16-hour incubation, the cells were harvested onto glass-fiber
filter mats, and the3H-TdR incorporation by
CTLL-2 was assessed by liquid scintillation spectrophotometry (1205
Betaplate, Pharmacia Wallac).
Cultures were set up and incubated as described above. On days 3
and 6, recombinant IL-2 was added to give a final concentration in the
wells of 5 U/mL on each occasion. On day 10 of culture,
1x104 51Cr-labeled
phytohemagglutinin–activated cells prepared from the original
donor spleen cells were added to the cultures as target cells. The
supernatants were harvested 4 hours later, and
the51Cr released was measured in a gamma
counter.
Frequencies of alloreactive Th cells were calculated by use of a
maximum likelihood statistical program with GLIM software (NAG Ltd) on
the basis of the method of Finney.45 The
proportion of negative wells at each sample size of responder cells is
linearly related to the frequency of responder cells according to the
Poisson distribution:
-logePneg=fX,
where Pneg is the proportion of negative wells, f
is the frequency of responder cells, and X is the number of responder
cells per well. The 95% confidence limits of the frequencies and
2 estimates of probability were calculated.
From the 2 values and degrees of freedom (the
number of responder dilutions minus one), probability estimates of the
data conforming to "single-hit" kinetics may be calculated. Assays
with values of P
.05 are likely to conform to single-hit
kinetics, ie, that a single cell type, the alloreactive IL-2–producing
Th cell, is limiting. Assays with P<.05 that may not
conform to single-hit kinetics were discarded. Frequencies are regarded
as different if their 95% confidence limits (
2 SD) do not
overlap.
Recipient (responder):anti-donor HTL and CTL frequencies were
compared with those generated between responder T cells and third-party
donor (stimulator) splenic APCs with equivalent HLA mismatch. An
additional control was included to establish the immunogenicity of the
donor spleen cells; 24 replicate cultures were set up containing
5x104 donor spleen cells and
5x104 third-party responder T cells. HTLf and
CTLf assays involving spleen cells that failed to give rise to 24 of 24
positive wells with the third-party responder T cells were
discarded.
Results
Top
Abstract
Introduction
Methods
Results
Discussion
References
All the recipients included in this study had angiographic
evidence of progressive chronic rejection as manifested by TxCAD.
Furthermore, all the heart grafts were mismatched for between four and
six HLA-A, -B, and -DR alleles. The third-party spleen cells used
as a control for each recipient were selected to have the same degree
of HLA mismatch as the recipient's donor cells. 
and 2, and the actual numerical frequencies,
together with 95% confidence intervals, are shown in the Table. In
past analyses, we have taken the figure of 1:100 000 as the
cutoff between high (>1:100 000) and low (<1:100 000) frequencies.
Indeed, in several independent studies, HTL and CTL frequencies
<1:100 000 were never observed in the face of four to six HLA antigen
mismatches25 26 when responder cells from normal
healthy individuals were used. Accordingly, we chose to define
donor-specific hyporesponsiveness as being present if the
recipient:anti-donor frequency was <1:100 000 and if the frequency
measured against the donor was a log-order of magnitude less than the
recipient: anti–third-party frequency. On this basis, donor-specific
hyporesponsiveness was detected in 5 of the 10 recipients. The HTLf in
the other five recipients were >1:100 000. Of the 5 recipients with
low HTLf, 4 also had low anti-donor CTLf (<1:100 000), and in 2 of
these, the CTLf (D and E) was actually below the limits of sensitivity
of the assay. In the 5th recipient (recipient H), although the CTLf was
>1:100 000, it was nonetheless significantly lower than that
estimated against the third-party spleen cells.
View larger version (17K):
[in a new window]
Figure 1. IL-2–producing T helper cell frequencies are
shown depicting the recipient:anti-donor ( 
) and recipient:anti-third
party (
) direct alloresponse. For recipients D, E, H, I, and J,
donor antigen-specific hyporesponsiveness is demonstrated as the
recipient:anti-donor frequencies are less than 1/100 000 and a log
order of magnitude lower than the respective recipient
anti–third-party frequency.
View larger version (16K):
[in a new window]
Figure 2. Cytotoxic T-cell frequencies are shown depicting
the recipient:anti-donor ( ) and recipient:anti-third party ()
direct alloresponse. For recipients D, E, I, and J, donor
antigen-specific hyporesponsiveness is again demonstrated. Although not
<1/100 000, patient H demonstrates a statistically significant lower
recipient:anti-donor frequency compared with the respective
anti–third-party frequency.
View this table:
[in a new window]
Table 1.
Discussion
Top
Abstract
Introduction
Methods
Results
Discussion
References
The specific coronary artery vasculopathy is the
manifestation of chronic rejection of the cardiac allograft (TxCAD). It
can, in many respects, be regarded as an inevitable consequence of the
transplantation process. Although both antigen- and
non–antigen-dependent mechanisms play a role in its evolution, immune
mechanisms undoubtedly make a significant contribution to its incidence
and progression.
Selected Abbreviations and Acronyms
APC
=
antigen-presenting cell
CTLf
=
cytotoxic T cells
HTLf
=
helper T cells
IL
=
interleukin
PBMC
=
peripheral blood mononuclear cell
TxCAD
=
transplant-associated coronary artery disease
Acknowledgments
This work was supported by grants received by P. Hornick from
the British Heart Foundation and the Royal College of Surgeons of
England.
References
Top
Abstract
Introduction
Methods
Results
Discussion
References
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W. F. Ng, M. Hernandez-Fuentes, R. Baker, A. Chaudhry, and R. I. Lechler Reversibility with Interleukin-2 Suggests that T Cell Anergy Contributes to Donor-Specific Hyporesponsiveness in Renal Transplant Patients J. Am. Soc. Nephrol., December 1, 2002; 13(12): 2983 - 2989. [Abstract] [Full Text] [PDF]
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 A. Freese and N. Zavazava HLA-B7 beta -pleated sheet-derived synthetic peptides are immunodominant T-cell epitopes regulating alloresponses Blood, May 1, 2002; 99(9): 3286 - 3292. [Abstract] [Full Text] [PDF]
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N. Najafian, A. D. Salama, E. V. Fedoseyeva, G. Benichou, and M. H. Sayegh Enzyme-Linked Immunosorbent Spot Assay Analysis of Peripheral Blood Lymphocyte Reactivity to Donor HLA-DR Peptides: Potential Novel Assay for Prediction of Outcomes for Renal Transplant Recipients J. Am. Soc. Nephrol., January 1, 2002; 13(1): 252 - 259. [Abstract] [Full Text] [PDF]
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R. J. Baker, M. P. Hernandez-Fuentes, P. A. Brookes, A. N. Chaudhry, H. T. Cook, and R. I. Lechler Loss of Direct and Maintenance of Indirect Alloresponses in Renal Allograft Recipients: Implications for the Pathogenesis of Chronic Allograft Nephropathy J. Immunol., December 15, 2001; 167(12): 7199 - 7206. [Abstract] [Full Text] [PDF]
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K. L. WOMER, J. R. STONE, B. MURPHY, A. CHANDRAKER, and M. H. SAYEGH Indirect Allorecognition of Donor Class I and II Major Histocompatibility Complex Peptides Promotes the Development of Transplant Vasculopathy J. Am. Soc. Nephrol., November 1, 2001; 12(11): 2500 - 2506. [Abstract] [Full Text] [PDF]
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 R. S. Lee, K. Yamada, S. L. Houser, K. L. Womer, M. E. Maloney, H. S. Rose, M. H. Sayegh, and J. C. Madsen Indirect recognition of allopeptides promotes the development of cardiac allograft vasculopathy PNAS, March 13, 2001; 98(6): 3276 - 3281. [Abstract] [Full Text] [PDF]
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C. A. Slachta, V. Jeevanandam, B. Goldman, W. L. Lin, and C. D. Platsoucas Coronary Arteries from Human Cardiac Allografts with Chronic Rejection Contain Oligoclonal T Cells: Persistence of Identical Clonally Expanded TCR Transcripts from the Early Post-Transplantation Period (Endomyocardial Biopsies) to Chronic Rejection (Coronary Arteries) J. Immunol., September 15, 2000; 165(6): 3469 - 3483. [Abstract] [Full Text] [PDF]
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 P. I. Hornick, P. D. Mason, R. J. Baker, M. Hernandez-Fuentes, L. Frasca, G. Lombardi, K. Taylor, L. Weng, M. L. Rose, M. H. Yacoub, et al. Significant Frequencies of T Cells With Indirect Anti-Donor Specificity in Heart Graft Recipients With Chronic Rejection Circulation, May 23, 2000; 101(20): 2405 - 2410. [Abstract] [Full Text] [PDF]
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R. S. Lee, K. Yamada, K. L. Womer, E. P. Pillsbury, K. S. Allison, A. E. Marolewski, D. Geng, A. D. Thall, J. S. Arn, D. H. Sachs, et al. Blockade of CD28-B7, But Not CD40-CD154, Prevents Costimulation of Allogeneic Porcine and Xenogeneic Human Anti-Porcine T Cell Responses J. Immunol., March 15, 2000; 164(6): 3434 - 3444. [Abstract] [Full Text] [PDF]
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S. Kusaka, A. P. Grailer, J. H. Fechner Jr., E. Jankowska-Gan, T. Oberley, H. W. Sollinger, and W. J. Burlingham Clonotype Analysis of Human Alloreactive T Cells: A Novel Approach to Studying Peripheral Tolerance in a Transplant Recipient J. Immunol., February 15, 2000; 164(4): 2240 - 2247. [Abstract] [Full Text] [PDF]
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J. D. Hosenpud, P. Hornick, P. Mason, M. Yacoub, M. Rose, R. Batchelor, and R. Lechler Direct Antigen Presentation and Chronic Rejection • Response Circulation, May 25, 1999; 99 (20): 2709 - 2712. [Full Text] |