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Center for Surgery Research, The Cleveland Clinic Foundation, Cleveland, OH 44195
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Abstract |
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 Top Abstract IntroductionMaterials and MethodsResultsDiscussionReferences |
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CB6F1
(H-2bxd) bone marrow chimeras were challenged with the MCA
205 fibrosarcoma (H-2b). The tumor grew progressively in
the H-2b-tolerant chimeras and stimulated an immune
response in tumor-draining lymph nodes. Tumor-sensitized lymph node T
cells were activated ex vivo with anti-CD3 and IL-2, then
adoptively transferred to sublethally irradiated BALB/c or C57BL/6
recipients bearing established intracranial MCA 205 tumors. The
transferred T cells eradicated MCA 205 tumors in BALB/c recipients and
demonstrated tumor specificity, but had no therapeutic efficacy in the
C57BL/6 recipients. These data establish that tumor-associated host
cell constituents provide sufficient Ag presentation to drive effector
T cell function in the complete absence of direct tumor recognition.
This effector mechanism has an evident capacity to remain operative in
circumstances of immune escape, where the tumor does not express the
relevant MHC molecules, and may have importance even at times when
direct CTL recognition also remains operative. |
Introduction |
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TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
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Despite progressive growth of weakly immunogenic murine tumors, an immune response is demonstrably generated. LNs draining the tumor are highly enriched for tumor-sensitized T cells that are functionally at a pre-effector stage of differentiation. Freshly acquired tumor-draining LN T cells have defects in signal transduction and are not therapeutically active upon immediate adoptive transfer into secondary hosts even with minimal tumor burdens (11). However, ex vivo activation of the sensitized T lymphocytes with anti-CD3 mAb or bacterial superantigens followed by culture in low concentrations of IL-2 induces rapid proliferation and simultaneous acquisition of potent effector function with maintenance of immunologic specificity (10, 12, 13). T cells generated by this process retain the ability to traffic to and mediate tumor regression in several distinct anatomic sites including intracranial (i.c.) and s.c. sites (14, 15). The antitumor response rendered by transferred T cells is dependent on tumor infiltration (16, 17). The requirement for infiltration coupled with specificity indicates that restimulation of tumor Ag-restricted T cells within the tumor and local effector mechanisms are operative.
As anticipated for an Ag-specific response, the pre-effector cells are
a minor subset of the tumor-draining LN T cells. In accord with other
analyses of Ag-driven T cell sensitization in vivo, tumor-reactive
pre-effector T cells have down-regulated surface expression of CD62L
(L-selectin) (18, 19, 20, 21). Isolation of the minor subset of
CD62Llow LN T cells before ex vivo activation
provides effector cells that are extremely potent, in stark contrast to
the lack of activity in the predominant population of
CD62Lhigh T cells (21). Our studies
to further define the qualitative properties of the
CD62Llow LN T cells demonstrated that either the
CD4+ or CD8+ subset of the
CD62Llow tumor-draining LN cells could
independently mediate tumor
regression5
(22). CD4+ T cells were
quantitatively more effective than CD8+ T cells
in certain anatomic sites such as the CNS and s.c. tissue. These sites
are more difficult to treat with combined cell therapy and have been
generally refractory to other types of cellular immunotherapy such as
tumor-infiltrating lymphocytes (23). The efficacy of
CD4+ T cells alone is particularly interesting
because the MCA 205 tumor does not express detectable levels of MHC
class II molecules. This suggests that other APC infiltrating the tumor
are capable of providing the relevant stimulus to the transferred
CD4+ T cells to initiate tumor regression.
Indeed, our studies have demonstrated that there is a substantial
percentage of I-A+, CD11b+
cells distributed throughout the tumor with the capacity to stimulate
CD4+ effector T cells (24). However,
it is theoretically possible that even transient expression of very low
levels of MHC class II molecules on tumor cells, induced, for example,
by IFN-
in vivo, could allow direct recognition and interaction by
CD4+ effector T cells without the intervention of
tumor-infiltrating APC. Prevailing hypotheses on the effector function
of tumor-reactive T cells involve direct cell contact to deliver
cytotoxic signals through surface molecules such as FasL or through
directed exocytosis of perforin (25). Tumor escape
variants with modulated MHC expression have been amply described in the
literature and pose an obstacle to the prevalent cancer immunotherapy
approaches to stimulate CD8+ cytolytic T cell
responses to tumor Ags (4, 8, 26). In this study, we
restricted Ag presentation to effector T cells by the MHC molecules of
the tumor-associated APC to demonstrate that curative tumor regression
can proceed even when direct tumor recognition is prevented.
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Materials and Methods |
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TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
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CB6F1 (H-2bxd), BALB/c, and B6 (C57BL/6)
mice at 6–8 wk of age were purchased from the Biologic Testing Branch,
Frederick Cancer Center Research and Development Center, National
Cancer Institute (Frederick, MD). B6 background IFN- knockout (KO)
(C57BL/6-IFNGtm1Ts) mice were purchased from The
Jackson Laboratory (Bar Harbor, ME). They were maintained in a specific
pathogen-free environment and fed ad libitum according to National
Institutes of Health guidelines.
Tumors
MCA 205 H12 was derived from the 3-methylcholanthrene-induced fibrosarcoma MCA 205 by limiting dilution cloning. MCA 207 G11 was similarly derived from MCA 207 by limiting dilution cloning. MCA 205 H12 and MCA 207 G11 were maintained by serial passage in vitro in complete medium (CM); RPMI 1640 supplemented with 10% heat-inactivated FCS, 0.1 mM nonessential amino acids, 1 mM sodium pyruvate, 2 mM L-glutamine, 100 µg/ml streptomycin, 100 U/ml penicillin, 50 µg/ml amphotericin B (all obtained from Life Technologies, Grand Island, NY), and 5 x 10-5 M 2-ME (Sigma, St. Louis, MO).
Flow cytometry
In vitro cultured tumor cells were treated with the indicated
concentration of murine IFN- for 24 h and harvested from
culture by trypsin/EDTA treatment. Single cell suspensions were
prepared from in vivo tumors by digestion in 0.1% collagenase type IV,
0.01% DNase I, and 2.5 U/ml hyaluronidase type V (Sigma) for 3 h
at room temperature as previously described (13).
Tumor-draining LNs were mechanically prepared as a single cell
suspension. All cells were incubated with Fc Block (PharMingen, San
Diego, CA) for 30 min on ice, then stained with the indicated
fluorochrome-conjugated Abs; anti-H-2Db,
anti-H-2Dd,
anti-I-Ab,
anti-I-Ad, anti-CD62L, anti-CD4,
anti-CD8, anti-CD11b, or isotype control rat IgG2, or mouse
IgG2a (all obtained from PharMingen) at 4°C for 30 min. Stained
cells, 104, were analyzed by flow cytometry using
the CellQuest software package (Becton Dickinson, San Jose,
CA).
Bone marrow transplantation
CB6 mice were treated with a single fraction of 10 Gy whole body
irradiation (WBI) from a 137Cs source. Bone
marrow obtained from BALB/c mice was injected i.v. into recipients
24 h after WBI. Mice received ciprofloxacin 100 µg i.p. once a
day for 20 days posttransplant. BALB/c CB6F1 bone marrow chimeras
were used to generate tumor-draining LN cells between 4 and 5 mo
posttransplant.
Activation of LN T cells
BALB/c CB6F1 bone marrow chimeras were inoculated s.c. with
1.5 x 106 MCA 205 H12 tumor cells in the
lower flank region bilaterally. Nine days later, tumor-draining
inguinal LNs were removed under sterile conditions and single cell
suspensions were prepared mechanically. Tumor-draining LN cells were
prepared similarly from IFN-KO mice except
that LNs were harvested 12 days after tumor inoculation. Cells were
resuspended in CM and were activated with immobilized anti-CD3 mAb
(145-2C11) in 24-well tissue culture plates at 4 x
106 cells per well in 2 ml CM in 5%
CO2 at 37.4°C for 2 days. After anti-CD3
activation, cells were harvested and further cultured in CM with 24
IU/ml of human recombinant IL-2 at 2 x
105/ml in gas-permeable culture bags (Baxter
Healthcare, Deerfield, IL) for 3 days. Cells were harvested, washed,
and resuspended in HBSS for adoptive transfer.
Adoptive immunotherapy
For recipients of IFN-KO effector
cells, B6 or IFN-KO mice were injected i.c.
with 1 x 105 MCA 205 H12 cells in 0.01 ml
HBSS. Three days later, mice were treated with 5 Gy WBI from a
137Cs source then injected i.v. with 15 x
106 effector cells suspended in 1 ml HBSS. For
recipients of BALB/c CB6F1 bone marrow chimera effector cells, B6
or BALB/c mice were conditioned with 5 Gy WBI from a
137Cs source. Two days later, they were injected
i.c. with 1 x 105 MCA 205 H12 or 1 x
105 MCA 207 G11 tumor cells in 0.01 ml of HBSS.
Three days later, mice were treated with 5 Gy cranial irradiation with
body shielding from a 137Cs source then injected
i.v. with 25 x 106 effector cells suspended
in 1 ml HBSS.
In vivo survival of transferred cells
Effector T cells were labeled with 5-(and-6)-carboxyfluorescein diacetate (CFDA) succinimidyl ester (Molecular Probes, Eugene, OR) as previously described (16). Briefly, cultured effector cells were washed twice with HBSS, and 1 x 107 cells/ml were incubated with CFDA succinimidyl ester (5 µM) in HBSS for 15 min at 37°C. Labeling was stopped by adding cold HBSS, and cells were washed twice with HBSS before adoptive transfer. C57BL/6 or BALB/c mice were conditioned with 5 Gy WBI from a 137Cs source then were inoculated 2 days later with 1 x 105 MCA 205 H12 tumor cells. Three days later, mice were treated with 5 Gy cranial irradiation with body shielding from a 137Cs source then injected i.v. with 25 x 106 fluorochrome-labeled effector cells. Mice were sacrificed 24 h, 48 h, and 7 days after adoptive transfer. Spleens were removed, mechanically disrupted, and treated with ammonium chloride to remove RBCs. Mononuclear cells were counted with a hemocytometer and an aliquot was analyzed by flow cytometry.
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Results |
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TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
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To determine the potential of the MCA 205 H12 tumor to present
Ags through MHC molecules, it was cultured in the presence of murine
IFN-. As shown in Fig. 1
A,
MCA 205 H12 expressed high basal levels of H-2Kb,
and this expression was up-regulated by 100 U/ml IFN-. MCA 205 H12
tumor cells are directly recognized by CD8+ T
cells derived from tumor-draining LN demonstrating that this tumor is
fully functional for Ag
presentation.5 In
contrast, MCA 205 H12 did not express I-Ab, nor
was it induced by treatment with 10,000 U/ml IFN- (Fig. 1B). A single cell suspension prepared from in vivo MCA 205
H12 tumor expressed H-2Kb and
H-2Db (Fig. 1, D and E). As
demonstrated in Fig. 1F, the tumor consisted of two
populations of cells, tumor cells that were I-A negative and CD11b
negative, and 
19% CD11b+,
I-A+ host accessory cells. Previous studies from
our laboratory confirmed that the CD11b+ cells
had phenotypic and functional characteristics of macrophages
(27). Consistent with the lack of tumor cell MHC class II
expression, CD4+ LN T cells were only stimulated
to secrete IFN- specifically by an MCA 205 tumor digest that
contains the I-A+ cells but not by MCA 205 H12
cells alone (22). Although aberrant expression of
allogeneic H-2 molecules has been described for some highly immunogenic
UV-induced tumors (28, 29), we detected neither expression
of H-2Kd and H-2Dd in vivo
(Fig. 1, D and E), nor that of
I-Ad (not shown). Thus, MCA 205 H12 would not be
expected to have the capacity to directly present Ags to
I-Ab-restricted T cells or, likewise, to
H-2d-restricted T cells.
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Regardless of the observed expression of MHC on tumor cells in
vitro, it is conceivable that modulation of tumor MHC expression could
occur during the height of the effector response in vivo, through
paracrine effects of soluble mediators, such as IFN-, released by T
cells or host cells. MCA 205 H12 tumor-draining LNs were obtained from
IFN-KO or normal B6 mice and were transferred
to IFN-KO or normal B6 mice bearing
established i.c. MCA 205 H12 tumors. All tumor-bearing mice were cured
whether or not the effector T cells produced IFN- (Fig. 2). T cells from IFN--deficient mice
were also effective in IFN-KO hosts
(p = 0.0006 compared with untreated mice).
Although late tumor recurrence occurred in two
IFN-KO mice treated with
IFN-KO T cells, the difference did not reach
statistical significance (p = .43). An
attenuating effect of host IFN- production on tumor progression was
also manifested in normal mice not treated with T cell transfer
compared with IFN-KO recipients (27 vs 21 days
median survival, respectively; p = 0.003).
Nevertheless, IFN- production was not an essential component of the
antitumor response mediated by the transferred effector T cells.
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CB6 mice (H-2bxd) were transplanted with
bone marrow from BALB/c mice following myeloablative WBI. The BALB/c
CB6F1 bone marrow chimeras were allowed to reconstitute their T
cell repertoire for 4 mo following the transplant. T cells in such mice
were tolerant of H-2b-expressing tissues but were
primed in secondary lymphoid tissues by APC derived from the
H-2d donor hemopoietic system. MCA 205 H12 tumors
grew progressively, expressed H-2Kb in the
chimeric hosts, and contained a significant population (40%) of
CD11b+, I-Ad cells but no
I-Ab cells (Fig. 3, C and D). Moreover, the tumor stimulated
hyperplasia in draining LN (average of 14.5 x
106 cells/LN compared with 1.2 x
106 per nondraining LN). The tumor-draining LNs
contained 40% T lymphocytes, and 14% of the T cells expressed low
levels of CD62L (L-selectin) (Fig. 3F). This was similar to
the profile of MCA 205 tumor-draining LNs in C57BL/6 mice
(21). The cells in the LN expressed
H-2d but not H-2b molecules
indicating that they were derived from the donor bone marrow (Fig. 3, G and H). Additionally, because the MCA 205 H12
clone has been maintained continuously in vitro since it was derived,
no I-Ab APC were inoculated into the
chimeras.
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BALB/c and B6 mice were treated with sublethal WBI, and, 2 days
later, MCA 205 H12 was inoculated i.c. The sublethal WBI before tumor
inoculation was necessary to permit growth of the allogeneic tumor
because nonirradiated BALB/c recipients were competent to reject
105 i.c. MCA 205 H12 cells (data not shown). The
established tumors were subsequently treated with local cranial
irradiation (5 Gy) followed by adoptive transfer of activated effector
T cells. We have previously demonstrated that local irradiation of an
established i.c. tumor is not essential but does augment the efficacy
of the transferred T cells (24). The tumor grew
progressively in the irradiated recipients and was equally lethal in
BALB/c and B6 recipients (Fig. 4). The
survival time in irradiated BALB/c mice was similar to irradiated B6
mice in the absence of effector T cell transfer consistent with a
subtherapeutic remnant alloreactive T cell or NK activity. The adoptive
transfer of 25 x 106 activated LN T cells
was able to cure an established tumor in the BALB/c recipients but had
no apparent therapeutic effect in the B6 recipients. Fig. 4, a
compilation of three independent experiments of identical design,
showed a highly significant survival difference for the treated BALB/c
mice compared with each of the other groups (p
< 0.0001). In contrast, there was no survival difference for B6 mice
treated with effector cells compared with untreated B6 mice
(p = 0.35). Likewise, treatment of B6 mice with
a higher dose of effector cells (5 x 107)
did not extend survival compared with untreated controls (data not
shown). The B6 mice all died from tumor progression as evidenced by
swelling of the skull and development of neurological dysfunction.
Tumor progression as the cause of death was confirmed by necropsy in
sentinel B6 mice treated with adoptive transfer (not shown).
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The MCA 205 tumor typically contains a significant population of
infiltrating macrophages. In BALB/c mice bearing i.c. MCA 205 H12
tumors, the expression of H-2d molecules was
observed on the CD11b+ macrophages, whereas the
CD11b- tumor cells expressed
H-2b (Fig. 5).
Thus, H-2d-restricted effector T cells derived
from the bone marrow chimeras were only presented with cognate Ags
through the tumor-infiltrating normal host cell constituents and not by
the tumor cells. A direct response of T cells from the chimeras to the
H-2b tumor cells was not apparent in vivo in the
B6 mice. Moreover, in vitro coculture of MCA 205 H12 tumor cells with
effector T cells did not elicit any IFN- secretion (data not shown).
To confirm that the tumor regression observed was Ag-specific rather
than mediated by an atypical allo-Ag response, MCA 205 H12-sensitized T
cells were transferred to BALB/c recipients bearing i.c. MCA 207 G11
tumors. MCA 207 G11 is a subclone of the MCA 207 fibrosarcoma
(H-2b). In previous experiments using syngeneic
B6 mice, we have demonstrated that MCA 207 Ags were not recognized by
MCA 205-sensitized LN cells (13). As demonstrated in Fig. 6, the transferred effector T cells did
not extend survival of mice bearing MCA 207 G11 tumors compared with
untreated mice (p = 0.9). In contrast, mice
bearing MCA 205 H12 tumors treated with transferred had significantly
prolonged survival compared with untreated mice
(p = 0.0017).
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We have used CFDA-labeled effector T cells to study the
trafficking and persistence of the transferred cells in tumor-bearing
hosts (16, 17). CFDA labeling does not affect the
antitumor effector function of the transferred T cells and permits
their identification for at least 1 wk following adoptive transfer.
Spleens were removed from irradiated tumor-bearing BALB/c or B6 mice
following the adoptive transfer of 25 x 106
CFDA-labeled effector T cells. Table I
documents the similar survival of transferred T cells in the BALB/c or
B6 recipients up to 7 days after adoptive transfer. Fig. 7 demonstrates that similar percentages
of CD4 and CD8 T cells were recovered from BALB/c and B6 recipients
48 h after transfer. Thus, the failure of the MCA 205
H12-sensitized chimeric T cells to function in the B6 recipients was
not caused by their rapid elimination.
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Discussion |
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TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
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In this experimental model, cross-priming of T cells by bone
marrow-derived APC was the predominant mechanism of sensitization to
naturally occurring tumor Ags. It has been previously documented that,
during the afferent phase of the immune response, Ags expressed in the
periphery are acquired by APC and presented in LNs in a MHC-restricted
fashion to prime both naive CD4 and CD8 T cells (35, 36).
Similarly, sensitization of T cells to foreign model tumor Ag was
demonstrated to occur through cross-priming (37). In the
BALB/c CB6F1 bone marrow chimeras, cross-priming to natural tumor
Ags was mediated by APC of the hemopoietic lineage thus restricted by
H-2d molecules. Importantly, the existence of
cross-priming through H-2d does not necessarily
exclude the possibility of direct sensitization of
H-2b-restricted CD8+ T
cells by tumor cells. In the BALB/c CB6F1 bone marrow chimeras,
thymic selection occurs in the presence of radio-resistant epithelium
expressing H-2b,d molecules, and naive T cells
restricted by H-2b are generated
(38, 39, 40). Thus, the opportunity for naive T cells with
H-2b specificity to become sensitized in
tumor-draining LN and become activated ex vivo through Ag-independent
anti-CD3 stimulation is available. Such
H-2b-restricted effector T cells would be equally
tumoricidal through their direct interactions with tumor in either the
B6 or BALB/c recipients. Therefore, the absence of any therapeutic
efficacy in B6 mice, even at supertherapeutic cell doses, strongly
argues that direct tumor priming of T cells is inconsequential in this
tumor model as it has been found in others (41). MCA 205
H12 does not metastasize to draining LN, even at very advanced stages
of growth so is unlikely to be present at the site of Ag presentation
to naive T cells. Furthermore, the MCA 205 H12 tumor cells do not
express costimulatory molecules or MHC class II molecules that are
typically required in model systems where direct sensitization is
evident (42, 43).
Cross-priming illustrates that the immune system uses specialized APC to communicate the presence of Ag and danger signals in the periphery to the protected environment of the LN, where the cellular architecture is optimized to generate an appropriate response by naive T cells. However, as immature DC acquire Ag in the periphery, the milieu can affect their differentiation (44). For example, the presence of TGF-ß expressed by many tumors during Ag acquisition causes APC to generate a deviant T cell response to a foreign Ag and loss of a delayed-type hypersensitivity reactivity (45). Thus, it is not predetermined that tumor Ag acquisition by DC will necessarily generate the type of T cell response that leads to tumor regression. Moreover, the nature of the Ags, their quantity, and presence of cognate CD4 responses during sensitization determine the outcome of cross-priming and can lead to either tolerization or augmentation of CD8 responses (46, 47, 48, 49). The mode of Ag presentation is likely to have great importance for priming T cell responses to progressive naturally occurring tumor Ags where aberrantly expressed or mutated proteins are contained within a predominantly normal array of self Ags. There is evidently some plasticity in the differentiation potential of tumor-sensitized T cells that can be manipulated by the conditions of ex vivo activation. The sensitized T cells in the tumor-draining LN do not prevent progressive tumor growth nor do they mediate tumor regression upon immediate adoptive transfer. However, sensitized LN T cells acquired potent Ag-specific reactivity following ex vivo activation, indicating that a critical differentiation step or functional change had occurred. This conveniently permitted us to determine the requirements for Ag presentation solely during the effector phase through adoptive transfer to secondary hosts.
The salient finding of this study is that tumor-infiltrating APC play an important role in the effector phase of the antitumor immune response and are sufficient to coordinate tumor regression with Ag-specific T cells in the absence of direct tumor recognition. DC are one differentiated form of hemopoietic precursors that are optimized to acquire Ag and stimulate naive T cells. Macrophages have some overlapping lineage and phenotypic characteristics with DC but perform distinct functions in peripheral tissues. Through their ability to acquire and process Ag, either macrophages or DC would have the capacity to convey the local presence of tumor Ag to effector T cells even when the T cells do not directly recognize tumor cells or do so poorly (50, 51, 52). This reactivation is likely critical for tumor-infiltrating CD4+ T cells and also for CD8+ T cells when the tumor has lost expression of the relevant MHC molecules (26). In addition, these experiments provoke an interesting question of whether the tumor-infiltrating APC might provide a more effective stimulus for CD8+ effector T cells than the tumor cells under most circumstances. We have previously demonstrated that infiltration of tumor by adoptively transferred T cells and costimulation of T cells through LFA-1 are both required for effector function (17, 53). Reactivation of adoptively transferred T cells in situ might be more efficiently provided by APC that typically express higher levels of LFA-1 ligands such as ICAM-1 and ICAM-2 than tumor cells. Although the current experiments were designed to only address whether indirect Ag presentation to effector T cells was sufficient, future experiments could potentially test the relative effectiveness of APC vs tumor cells for reactivation.
An important function of APC stimulation of effector
CD4+ and CD8+ T cells could
be the induction of cytokines with paracrine effects. Our previous
studies demonstrated the necessity of CD4+ T cell
participation in the adoptive immunotherapy of i.c. or s.c. MCA 205
tumor (13, 15). Likewise, CD4+ T
cell-dependent effector mechanisms have also been demonstrated in a
vaccination-challenge model (54). Interestingly,
CD4+ CD62Llow T cells
isolated from tumor-draining LN can cure a tumor that does not express
detectable levels of MHC class II, following in vitro and in vivo
depletion of CD8+ T cells. This observation
encouraged us to re-examine the concept of "helper function" in
this tumor model system. Rather than merely serving as a source of IL-2
for cytotoxic CD8+ T cells, apparently the
CD4+ T cells mediated an antitumor response
through paracrine effects of additional secreted cytokines
(55). Although IFN- is an important cytokine with
paracrine function, our experiments demonstrated that IFN--deficient
T cells could nevertheless cure tumors in IFN--deficient hosts.
Thus, there are sufficient redundant effector mechanisms mediated
through additional cytokines.
The tumor-infiltrating APC could also contribute a critical effector function beyond Ag presentation to T cells. The large majority of the APC that infiltrate the MCA 205 tumors have phenotypic and functional characteristics of macrophages. Activated macrophages can secrete inflammatory cytokines and reactive substances such as NO with paracrine effects as well as perform phagocytosis. Their distribution throughout the tumor would permit localized display of acquired tumor Ags to specific T cells. The specificity provided by the T cells could anatomically localize activation of nonspecific cytolytic function by macrophages to limit collateral damage to adjacent normal structures. Such an anatomically localized mechanism of tissue destruction has obvious importance in delicate structures such as the CNS.
Generation of effector T cells restricted by the APC of the tumor-bearing host but unable to interact directly with the tumor provides independent experimental confirmation that dominant indirect presentation of tumor Ags can occur, not only during initial T cell sensitization, but also during the effector phase of tumor rejection. The indirect mechanism of tumor eradication described here does not preclude other mechanisms, such as direct cytotoxicity, from being predominant under conditions where direct interactions of effector T cells with the tumor is permitted. Nonetheless, the critical clinical importance of T cell effector mechanisms that remain operative in the face of tumor escape through modulation of MHC expression is already apparent (4, 5, 8, 26, 56). This report confirms the ability of adequately implemented T cell adoptive therapy fully to withstand such escape modulations. It also hints at the potential use of augmenting APC numbers and function at the effector phase through systemic delivery of cytokines in conjunction with adoptive transfer of suitably primed and activated T cells.
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Footnotes |
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2 Address correspondence and reprint requests to Dr. Gregory E. Plautz at his current address: Department of Pediatrics, Yale University School of Medicine, 4087 LMP, 333 Cedar Street, New Haven, CT 06520-8064.
3 Current address: 504 Goshonishe Park Homes Rakurakuso, 464 Santei-cho Nakadachiuridori Muromachinishiiru, Kamigyo-ku, Kyoto 602-0915 Japan.
4 Abbreviations used in this paper: LN, lymph node; i.c., intracranial; WBI, whole body irradiation; CFDA, 5-(and-6)-carboxyfluorescein diacetate; KO, knockout; CM, complete medium.
5 Peng, L., D. E. Weng, G. E. Plautz, S. Shu, and P. A. Cohen. 2000. Helper-independent, L-selectinlow CD8+ T cells with broad anti-tumor efficacy are naturally sensitized during tumor progression. Submitted for publication.
Received for publication May 2, 2000. Accepted for publication July 14, 2000.
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References |
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TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
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A. S. Lonsdorf, H. Kuekrek, B. V. Stern, B. O. Boehm, P. V. Lehmann, and M. Tary-Lehmann Intratumor CpG-Oligodeoxynucleotide Injection Induces Protective Antitumor T Cell Immunity J. Immunol., October 15, 2003; 171(8): 3941 - 3946. [Abstract] [Full Text] [PDF]
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N. Fujita, H. Kagamu, H. Yoshizawa, K. Itoh, H. Kuriyama, N. Matsumoto, T. Ishiguro, J. Tanaka, E. Suzuki, H. Hamada, et al. CD40 Ligand Promotes Priming of Fully Potent Antitumor CD4+ T Cells in Draining Lymph Nodes in the Presence of Apoptotic Tumor Cells J. Immunol., November 15, 2001; 167(10): 5678 - 5688. [Abstract] [Full Text] [PDF]
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L. Peng, J. C. Krauss, G. E. Plautz, S. Mukai, S. Shu, and P. A. Cohen T Cell-Mediated Tumor Rejection Displays Diverse Dependence Upon Perforin and IFN-{gamma} Mechanisms That Cannot Be Predicted From In Vitro T Cell Characteristics J. Immunol., December 15, 2000; 165(12): 7116 - 7124. [Abstract] [Full Text] [PDF]
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L. Peng, J. Kjaergaard, G. E. Plautz, D. E. Weng, S. Shu, and P. A. Cohen Helper-Independent, L-Selectinlow CD8+ T Cells with Broad Anti-Tumor Efficacy Are Naturally Sensitized During Tumor Progression J. Immunol., November 15, 2000; 165(10): 5738 - 5749. [Abstract] [Full Text] [PDF]
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). B6
mice treated with 25 x 106 activated LN cells (
)
or no cell transfer (
). Each group consists of 15 mice and is
compiled from three identically designed experiments each containing
five mice per group. Treatment with effector T cells improved survival
in BALB/c recipients (p < 0.001 by rank sum test
compared with each other group).
