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*
Department of Immunology, Institute of Medical Microbiology and Hygiene, University of Freiburg, Freiburg, Germany; and
Department of Internal Medicine I (Hematology/Oncology), Freiburg University Medical Center, Freiburg, Germany
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Abstract |
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 Top Abstract IntroductionMaterials and MethodsResultsDiscussionReferences |
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Introduction |
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TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
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It is established that an antitumor immune response occurs in various malignancies. Different cell types, including NK cells, dendritic cells, macrophages, helper T cells, and CTL can cooperate to generate an immune response. Several tumor-associated Ags recognized by CD8+ T lymphocytes have been identified (reviewed in Ref. 10). Long-term T cell lines derived from the tumor mass, expanded and differentiated in the presence of IL-2, have been shown to specifically recognize tumor Ags and to exhibit MHC-restricted lysis specific for autologous tumor cells (11, 12, 13). Consistent with the predominant role of CD8+ T cells in antitumor immunity, adoptive transfer of tumor-specific CTL has been shown to prevent tumor outgrowth or to result in marked regression of established tumors (14, 15). It is likely that the CTL activity of T cell lines or clones derived from tumor-infiltrating lymphocytes (TIL)3 is due to the addition of high doses of IL-2 for their maintenance. Antitumor CTL responses have also been generated from PBMC, spleen cells, and tumor-draining lymph nodes for the development of immunotherapies for cancer treatment (16). In vitro stimulation of these cells with tumor Ag in the presence of exogenous cytokines was required to detect a significant CTL activity.
Many attempts have been performed to analyze TIL obtained directly from fresh tumors. However, functional studies using ex vivo-isolated TIL are difficult because of the low yield of the lymphocytes recovered. In the present report, we describe a melanoma model with a defined tumor-associated Ag to study tumor-specific CD8+ T cells freshly isolated from a tumor mass. B16.F10 melanoma cells were transfected with a minigene encoding the sequence of residues 33 to 41 (GP33 peptide) of the glycoprotein from the lymphocytic choriomeningitis virus (LCMV). These B16.F10GP33 melanoma cells, which expressed the H-2Db-restricted GP33 CTL epitope, were transferred s.c. into syngeneic C57BL/6 (B6) mice and into B6 mice transgenic for the LCMV GP33-specific P14 TCR (P14 TCR mice) (17). Using this new model we addressed the following questions: 1) Are there specific CD8+ T cells infiltrating the tumor mass? 2) Do these TIL exhibit specific cytolytic activity or are they tolerized by the tumor cells? 3) Can TIL induce tumor regression? 4) does the CTL response select for Ag-loss variants in vivo? and 5) do GP33-specific T cells induced by a LCMV infection in vivo mediate antitumor activity on preestablished tumors?
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Materials and Methods |
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TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
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B6 mice were obtained from our breeding colony or from Harlan
Winkelmann (Borchen, Germany). The P14 TCR mice, line 318 and line 327,
expressing a V
2/Vß8 TCR specific for amino acids (aa) 33–41 (GP33
peptide, KAVYNFATM) of the LCMV glycoprotein in association with the
H-2Db molecule, have been described previously (17, 18). Line 318 expresses the transgenic TCR on 50 to 60% of
CD8+ T cells and has a normal CD4 to CD8 ratio, whereas
line 327 expresses the transgenic TCR on 85 to 95% of CD8+
T cells and has a highly skewed CD4 to CD8 ratio. Line 327 back-crossed
onto the Db mutant mouse strain B6.C-H-2bm13
(Kb, Dbm13) has been described previously
(19). Male and female mice of between 8 and 16 wk of age
were used. Mice were bred and kept in a conventional mouse house
facility.
Cell lines
The murine melanoma cell subline B16.F10, originally established by Prof. I. Fidler (20), was provided by Dr. H. Pahl (Klinik fur Tumorbiologie, Freiburg, Germany). B6.F10GP33 tumor cells were derived from parental B16.F10 cells by gene transfection using transfectam (Promega, Mannheim, Germany). The LCMV GP33 minigene was generated by cloning primers Kbg146 (5'-CC GGT GCC ACC ATG AAA GCT GTG TAC AAT TTC GCC ACC TGT TGA G-3') and Kbg147 (5'-GAT CC TCA ACA GGT GGC GAA ATT GTA CAC AGC TTT CAT GGT GGC A-3') corresponding to the LCMV GP33 epitope (M-KAVYNFATM) in the PinAI and BamHI restriction sites of the ß-actin-driven expression vector pActin-IRES-TK-Neo (NTS) (21). The resulting transfectants were cloned and screened for GP33 expression by CTL assays. The B6.F10GP33 melanoma line (clone 20) used in this study was kept in culture under G418 (200 µg/ml) (Life Technologies, Gaithersburg, MD) selection. EL-4 (H-2b), a thymoma cell line, was used as target cells. Cells were cultured in DMEM high glucose, supplemented with 10% heat-inactivated FCS, nonessential amino acids, glutamine, streptomycin, and penicillin (all from Life Technologies).
Tumor cell inoculation
Mice were injected s.c. into the right flank with 106 B16.F10 or B16.F10GP33 tumor cells in 100 µl PBS. Mice were checked for the presence of a palpable tumor, and tumor growth was measured every third day with a caliper. Tumor size was calculated as the product of bisecting tumor diameters. Mice bearing a tumor with a diameter >15 mm were killed according to animal reglementation. Experimental groups consisted of three to five mice.
Virus
The LCMV-WE isolate used in this study was originally obtained from Dr. Lehmann-Grube (Heinrich Pette Institut, Hamburg, Germany). It was then propagated on L929 fibroblast cells and quantified by virus plaque assay as described (22). Mice were infected i.v. with 200 plaque-forming units of LCMV-WE.
TIL isolation
TIL were purified from tumors (100–150 mm2) grown in B6 or in P14 TCR transgenic mice. After mincing fresh tumors, TIL were isolated by centrifugation over a Ficoll gradient (Pharmacia, Uppsala, Sweden). T cells were purified using immunomagnetic separation (Macs, Miltenyi Biotec, Bergisch-Gladbach, Germany) on RS+ columns (Miltenyi). Magnetic beads conjugated with anti-Thy-1.2 mAb were used as recommended by the manufacturer (Miltenyi). From 1 to 3 x 105 TIL were recovered per B6 mouse infected with LCMV or per P14 TCR transgenic mouse bearing B16.F10GP33 tumors. The isolated cells consisted of 40 to 60% of CD8+ T cells, as judged by anti-CD8 Ab staining.
Flow cytometry
Staining was performed in PBS containing 2% FCS, 0.1%
NaN3. For detection of TCR transgenic T cells, splenocytes
and TIL were incubated with FITC-conjugated anti-CD8 mAb (clone 53;
Life Technologies), phycoerythrin-conjugated anti-TCRV2 mAb
(PharMingen, San Diego, CA) and biotinylated anti-TCRVß8 mAb
(PharMingen), followed by second-step Tricolor-streptavidin (Caltag,
South San Francisco, CA). For the characterization of surface markers,
TIL and spleen cells were stained with FITC-labeled anti-CD8, and
biotinylated anti-CD62L, or anti-Fas mAb (all from PharMingen),
followed by phycoerythrin-streptavidin (Caltag). Cells were analyzed on
a FACSort flow cytometer (Becton Dickinson, Mountain View, CA) using
CELLquest software.
Generation of primary CTL response in vitro
Responder spleen cells (5 x 106) from P14 TCR mice (line 318) were cultured with B6 stimulator spleen cells (2 x 106) coated with 10-6 M GP33 peptide in 1.5 ml of Iscove’s modified Dulbecco’s medium containing 10% FCS supplemented with antibiotics and ß-mercaptoethanol in 24-well culture plates at 37°C. After 3 days, cells were harvested and CTL activity was determined.
Cytotoxicity assay
Cytolytic activity of spleen cells as well as freshly isolated TIL was assayed in a standard 51Cr-release assay as previously described (23). Briefly, EL-4, B16.F10, and B16.F10GP33 were used as target cells. EL-4 and B16.F10 target cells were coated with GP33 peptide or with the control Db-binding adenovirus peptide 234–243 (E1A peptide, SGPSNTPPEI) at a concentration of 10-6 M and were labeled simultaneously with 250 µCi 51Cr for 2 h at 37°C. Afterward, they were washed three times in RPMI 1640 medium. Spleen cells and TIL used as effector cells were resuspended in DMEM/10% FCS and were incubated in 96-well round-bottom plates with target cells at various ratios in a final volume of 200 µl. After a 5-h to 15-h incubation period at 37°C in 5% CO2, 70-µl supernatants were harvested and counted. The ratio of CD8+ T cells to target cells was calculated from flow cytometric analysis of effector cells. CTL activity of in vitro-stimulated spleen cells against B16.F10 tumor cells was measured in a 6-h 51Cr-release assay. Activated spleen cells were resuspended at various concentrations to give final effector CD8+ T cells to target cell ratios ranging from 100:1 to 0.02:1. Ex vivo CTL activity of spleen cells and TIL against EL-4 target cells was measured in a 15-h assay. Results were expressed as percentage of specific lysis = (experimental release (cpm) - spontaneous release (cpm))/(maximum release (cpm) - spontaneous release (cpm)) x 100.
Adoptive transfer of LCMV-immune cells
Spleen cells (5 x 107) containing 40 to 55% CD8+ T cells were collected from LCMV-immune B6 mice 8 days after LCMV infection and were injected i.v. in a volume of 0.5 ml medium without FCS into B6 mice bearing small, palpable, or no tumors.
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Results |
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TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
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We have used the immunodominant CD8+ T cell epitope of
LCMV (glycoprotein aa 33–41 = GP33) in H-2b mice as a
tumor-associated model Ag. B16.F10 melanoma (H-2b) cells
were transfected with a minigene encoding the
H-2Db-restricted LCMV GP33 epitope and expression was
tested by 51Cr release assays using GP33-specific CTL. As
shown in Figure 1
a,
GP33-transfected B16.F10 melanoma cells (B16.F10GP33) were
efficiently lysed by day 8 LCMV-immune effector cells from B6 mice and
also by in vitro-activated spleen cells from P14 TCR mice, which
express GP33-reactive TCR. The CTL activity of effector cells was GP33
specific, since these cells also lysed B16.F10 target cells loaded with
the GP33 peptide (Fig. 1b), but did not recognize these
target cells coated with an irrelevant Db-binding peptide
from the adenovirus (Fig. 1c). Thus, the
B16.F10GP33 transfectant used in this study was efficiently
recognized both by polyclonal LCMV-specific CD8+ T cells
from B6 mice and by monoclonal CD8+ T cells from P14
TCR mice.
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To assess the effect of the GP33 expression on B16.F10 tumor
growth, naive and LCMV-immune B6 mice were inoculated s.c. with
parental and GP33-transfected melanoma cells. As shown in Figure 2, a and b, both
parental and GP33-transfected melanoma cells grew at a similar rate in
naive B6 mice. In contrast, LCMV-immune B6 mice that had been infected
with LCMV 6 to 8 wk before tumor cell injection were completely
protected against tumor growth of B16.F10GP33 but not of
parental B16.F10 melanoma cells (Fig. 2, c and
d).
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f). The day on which palpable B16.F10GP33
tumors could be detected varied; B16.F10GP33 tumors were
detected 1 to 3 wk later in the P14 TCR mice, when compared with the
B16.F10 tumor growth (Fig. 2e). However, once the tumor was
established, B16.F10GP33 cells grew as quickly in P14 TCR
mice as in naive B6 mice. Similar results were obtained when P14 TCR
mice from line 327 (90% of CD8+ T cells express the
transgenic TCR) were inoculated with B16.F10 and
B16.F10GP33 tumor cells (Fig. 2, g and
h).
To test whether the delay in tumor take in P14 TCR mice was due to
direct presentation of the GP33 peptide by B16.F10GP33
melanoma cells or due to cross-priming involving host APC, P14 TCR mice
(line 327) exhibiting a mutation in their Db molecule
(H-2Dbm13) were analyzed. The mutant Dbm13
molecule cannot present the GP33 peptide but can positively select the
GP33-specific transgenic TCR (19). Appearance of palpable
B16.F10GP33 tumors in P14 TCR Dbm13 mice was
delayed when compared with parental B16.F10 tumors (Fig. 2, i and j), suggesting direct presentation of the
GP33 peptide by B16.F10GP33 tumor cells in vivo.
To exclude the possibility that tumor cells that grow in P14 TCR mice represent Ag loss variants, B16.F10GP33 tumors were isolated from P14 TCR mice and tested in vitro for GP33 expression by 51Cr release assays using GP33-specific CTL. A total of 15 out of 16 freshly isolated B16.F10GP33 tumors were efficiently recognized by GP33-reactive T cells, indicating that B16.F10GP33 tumors from P14 TCR mice are not Ag loss variants (not shown). Taken together, these data show that despite the high frequencies of GP33-specific T cells in P14 TCR mice and the ability of activated TCR transgenic cells to lyse B16.F10GP33 tumor cells, B16.F10GP33 tumors grew progressively in P14 TCR mice. In striking contrast, B16.F10GP33 tumors did not grow in LCMV-immune B6 mice that exhibit 100-fold lower frequency of GP33-specific CTLp which, however, have been primed by LCMV infection.
TIL but not peripheral T cells from tumor-bearing P14 TCR mice exhibit ex vivo GP33-specific cytolytic activity
One possibility to explain B16.F10GP33 tumor growth in
P14 TCR mice may be the inefficiency of in vivo activation of
GP33-specific CD8+ T cells by B16.F10GP33
melanoma cells, which lack costimulatory molecules. To determine
whether B16.F10GP33 melanoma cells were able to activate
GP33-specific T cells in vivo, ex vivo cytolytic activity of spleen
cells and of TIL directly isolated from the fresh tumors of P14 TCR
mice was determined. As shown in Figure 3, a and
b, spleen cells from
tumor-bearing P14 TCR (line 318 and line 327-Dbm13) did not
lyse target cells pulsed with GP33 peptide. Similar results were
obtained from inguinal lymph nodes draining the tumor (data not shown).
In contrast, TIL isolated from these mice exhibited high GP33-specific
lytic activity (Fig. 3, c and d). The ex vivo
cytolytic activity of TIL from tumor-bearing P14 TCR mice was
comparable with that of LCMV-specific CTL from spleens of day 8
LCMV-immune B6 mice on a cell per cell basis (Fig. 3, e and
f). No cytolytic activity of TIL from P14 TCR mice, which
bore parental B16.10 tumors, could be detected (not shown). The finding
that TIL isolated from tumor-bearing P14 TCR H-2Dbm13 mice
exhibit GP33-specific lytic activity further supports the view that
B16.F10GP33 melanoma cells directly activated TCR
transgenic T cells without cross-priming in vivo.
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(right), CD8+ T
cells isolated from TIL displayed an activated phenotype with increased
forward scatter, down-regulated TCR and CD62L, and up-regulated
Fas/CD95 expression. In contrast, peripheral T cells isolated from
spleen (Fig. 4, left) and inguinal lymph nodes (not shown)
from these tumor-bearing P14 TCR mice exhibited a naive phenotype.
Furthermore, 28% of CD8+ T cells isolated from TIL of a
B16.F10GP33 tumor-bearing P14 TCR mouse expressed CD25
(IL-2R) whereas only 4 to 5% of the CD8+ T cells from
spleen or lymph node of the same mouse expressed this marker.
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LCMV infection of B6 mice induces a strong GP33-specific CTL
response. It was therefore of interest to examine whether this
efficient CTL activity was able to control preestablished
B16.F10GP33 tumors. Parental and GP33-transfected B16.F10
tumor cells were injected s.c. into naive B6 mice. After detection of
palpable tumors (day 9–10 after tumor cell injection), mice were
infected with LCMV and tumor growth was measured. As shown in Figure 5a, two out of four parental
B16.F10 tumors grew more slowly in B6 mice after the LCMV infection
when compared with uninfected mice. Such a result could be explained by
bystander effects of the viral infection (e.g., NK cells induced by
INF-
). The data from Figure 5b shows that the delay of
B16.F10GP33 tumor growth was evident very early (in
contrast to Fig. 5a) after LCMV infection in all mice
analyzed (5/5). However, 1 to 2 wk after LCMV infection, tumor growth
of B16.F10GP33 cells was comparable in uninfected and
LCMV-infected B6 mice. To test the possibility that the tumor cells
that grow in LCMV-infected mice represent Ag loss variants,
B16.F10GP33 tumors were isolated and tested. As shown in
Figure 5c, all four B16.F10GP33 tumors, freshly
isolated from LCMV-infected B6 mice, were efficiently recognized by
LCMV effector cells from B6 mice, indicating that
B16.F10GP33 tumors in LCMV-infected B6 mice are not Ag loss
variants.
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It has been suggested that tumor cells tolerize tumor-specific T
cells. We therefore examined whether GP33-specific CTL could be induced
in B16.F10GP33 tumor-bearing B6 mice by LCMV infection.
Control B6 mice and B6 mice bearing palpable B16.F10 or
B16.F10GP33 tumors were infected with LCMV, and 10 days
later the cytolytic activity of spleen cells and TIL was assessed by
51Cr release assay. As shown in Figure 6, spleen cells from LCMV-infected
B16.F10GP33 tumor-bearing mice (Fig. 6c)
exhibited high GP33-specific CTL activity comparable with that of
control B6 (Fig. 6a) and B16.F10 tumor-bearing mice (Fig. 6b). Similarly, TIL isolated from B16.F10GP33
tumors of LCMV-infected B6 mice were highly cytolytic against
GP33-coated target cells (Fig. 6d). Thus, these data show
that GP33-specific CD8+ T cells were not tolerized by the
B16.F10GP33 tumor and that highly active GP33-specific CTL
were found at the tumor site.
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Next, we investigated whether the failure of the LCMV infection to
prevent growth of preestablished B16.F10GP33 tumors was due
to the lag time (6–8 days) between LCMV infection and induction of CTL
response. Therefore, day 8 LCMV-immune effector T cells (5 x
107) were transferred into B6 mice bearing preestablished
B16.F10GP33 tumors (20–40 mm2). As shown in
Figure 7a, adoptive transfer
of GP33-specific cells leads to dramatic decrease of tumor size; in two
out of three mice, no palpable tumor could be detected 2 to 3 days
after transfer. However, after a delay of 6 to 7 days without
significant tumor growth, B16.F10GP33 tumors grew in these
mice at a similar rate as in control B6 mice. LCMV-specific effector
CTL injected repetitively (three times) at 6- to 7-day intervals were
also not able to permanently eliminate preestablished
B16.F10GP33 tumors (Fig. 7b). Most of the
B16.F10GP33 tumors isolated from these mice were not Ag
loss variants, since five out of six tumors were readily recognized by
LCMV-specific effector cells in vitro (Fig. 7, c and
d). Finally, we examined whether the day 8 LCMV immune
effector T cells can prevent the growth of B16.F10GP33
tumors when transferred into B6 mice on the same day as the tumor. As
shown in Figure 8, adoptive transfer of
LCMV-specific cells prevented B16.F10GP33 tumor growth, but
did not affect the growth of parental B16.F10 tumor cells.
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Discussion |
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TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
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The selection of tumor Ag loss variants would easily explain the failure of the immune system to control the B16.F10GP33 tumor growth. The role of a tumor-specific CTL response in the in vivo selection of Ag loss variants has been suggested after analyzing Ags expressed on human melanoma cell lines derived from metastases appearing at intervals of several years (9, 32). In our system, most of the freshly isolated B16.F10GP33 tumors from P14 TCR mice (15/16) or from LCMV-infected or adoptively transferred B6 mice (9/10) still expressed GP33, since they were efficiently recognized by GP33-reactive CTL in vitro. Thus, despite a high GP33-specific CTL activity at the tumor site, only few GP33 loss variants were selected in vivo in the tumor model analyzed here.
Immunosuppressive activity through production of immunoregulatory
cytokines, such as TGF-ß and IL-10, by tumor cells may paralyze the
immune system in tumor-bearing hosts. In addition to this latter
mechanism, recent data correlated the immunosuppressive activity of
NK1.1+ T cells derived from the TIL of B16 melanoma with
their production of TGF-ß (33). The release of IL-10 by
CD8+ T cells from murine fibrosarcoma-draining lymph nodes
was also associated with a suppressed anti-tumor response in vivo
(34). We found that TIL from LCMV-infected
B16.F10GP33 tumor-bearing B6 mice elicited strong
GP33-specific CTL activity, comparable with that of spleen cells from
the same mice. This result argues against a GP33-specific
immunosuppression at the tumor site. Type 1-like lymphokine production
(IL-2, INF-, granulocyte-macrophage-CSF, and TNF-) was shown to
play a role in the regression of murine tumors by promoting tumor Ag
recognition (35). The production of such lymphokines by
GP33-specific TIL may overcome immunosuppression mediated by putative
immunosuppressive factors. The lymphokines secreted by TIL in our model
are currently under investigation. We cannot exclude the possibility
that defective cytokine production resulting from partial activation of
the tumor reactive T cells may explain B16.F10GP33 tumor
establishment in our system, as recently reported in human melanoma
(36).
Adoptive transfer of tumor-reactive T lymphocytes has been shown to prevent tumor growth or to result in regression of established tumors (37). Thus, Bloom et al. (38) demonstrated that a CTL line raised from splenocytes by repeated in vitro stimulation with the TRP-2 peptide specific for the B16 melanoma was therapeutic against 3-day-old established pulmonary metastases. In contrast, our data indicate that adoptive transfer of LCMV-immune effector cells or LCMV infection delayed, but did not prevent, the growth of established B16.F10GP33 tumors. This result fits in well with recent data from a double transgenic model, which demonstrated that LCMV-activated CD8+ T cells destroyed GP33-expressing pancreatic tumor cells and reduced tumor mass, without, however, definitive tumor clearance (39). It is interesting to note that in our system GP33-specific T cells were able to prevent the growth of the B16.F10GP33 tumor when CTL and tumor cells were injected at the same time point. LCMV induces a strong immune response dominated by LCMV-specific cytotoxic CD8+ T cells, which results in solid and long-term protective CTL memory in vivo (40). Surprisingly, these CD8+ T cells were not efficient in long-term protection against preestablished B16.F10GP33 tumor growth. FasL expressed on tumor cells may contribute to the immune privilege of tumors, and recent data suggest that B16.F10 tumor cells may counterattack anti-tumor activity by inducing apoptosis of T cells via the CD95L (8). Freshly isolated CD8+ TIL from P14 TCR mice bearing B16.F10GP33 tumors expressed high levels of Fas when compared with CD8+ T cells from spleen or inguinal lymph nodes. The high level expression of Fas at the TIL surface may correlate with a high sensitivity to CD95-mediated apoptosis.
It is striking that the B16.F10GP33 tumor grew in P14 TCR mice (GP33-specific CTLp: 1/1 to 1/2 of CD8) but did not grow in LCMV memory B6 mice (GP33-specific CTLp: 1/100 of CD8). This illustrates the importance of the activation state of the responding T cell population. In contrast to naive GP33-specific CD8+ T cells from P14 TCR mice, GP33-specific CD8+ memory T cells may immediately prevent tumor growth by direct cell lysis and/or increased cytokine production, since LCMV-specific memory T cells display ex vivo anti-GP33 CTL activity (41, 42) and secrete higher amounts of cytokines than their naive counterparts (our unpublished observations). Additionally, memory T cells may be less dependent on costimulation than naive T cells for full-blown activation, including clonal expansion and effector cell differentiation.
We conclude that despite the strong ex vivo cytolytic activity of TIL, these cells fail to prevent tumor establishment. Furthermore, LCMV infection or adoptive transfer of LCMV-immune effector cells only delayed the growth of an established tumor. These results point out the difficulty of maintaining efficient long-term anti-tumor activity in vivo. The challenge now is to elucidate the mechanism of tumor escape in this model and to maintain and improve TIL activity in vivo.
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Acknowledgments |
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Footnotes |
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2 Address correspondence and reprint requests to Prof. Dr. Hanspeter Pircher, Institute of Medical Microbiology and Hygiene, Department of Immunology, Hermann-Herder-Strasse 11, University of Freiburg, D-79104 Freiburg, Germany. E-mail address:
3 Abbreviations used in this paper: TIL, tumor infiltrating lymphocytes; LCMV, lymphocytic choriomeningitis virus; B6, C57BL/6 mice; P14 TCR mice, LCMV GP33-specific TCR transgenic mice; aa, amino acid.
Received for publication February 17, 1998. Accepted for publication April 30, 1998.
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TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
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. J. Exp. Med. 166:991. and tumor necrosis factor have a role in tumor regressions mediated by murine CD8+ tumor-infiltrating lymphocytes. J. Exp. Med. 173:647.This article has been cited by other articles:
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Y. Huang, N. Obholzer, R. Fayad, and L. Qiao Turning On/Off Tumor-Specific CTL Response during Progressive Tumor Growth J. Immunol., September 1, 2005; 175(5): 3110 - 3116. [Abstract] [Full Text] [PDF]
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S. Wei, I. Kryczek, L. Zou, B. Daniel, P. Cheng, P. Mottram, T. Curiel, A. Lange, and W. Zou Plasmacytoid Dendritic Cells Induce CD8+ Regulatory T Cells In Human Ovarian Carcinoma Cancer Res., June 15, 2005; 65(12): 5020 - 5026. [Abstract] [Full Text] [PDF]
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M. Koneru, D. Schaer, N. Monu, A. Ayala, and A. B. Frey Defective Proximal TCR Signaling Inhibits CD8+ Tumor-Infiltrating Lymphocyte Lytic Function J. Immunol., February 15, 2005; 174(4): 1830 - 1840. [Abstract] [Full Text] [PDF]
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F. Hirano, K. Kaneko, H. Tamura, H. Dong, S. Wang, M. Ichikawa, C. Rietz, D. B. Flies, J. S. Lau, G. Zhu, et al. Blockade of B7-H1 and PD-1 by Monoclonal Antibodies Potentiates Cancer Therapeutic Immunity Cancer Res., February 1, 2005; 65(3): 1089 - 1096. [Abstract] [Full Text] [PDF]
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Y. Lou, G. Wang, G. Lizee, G. J. Kim, S. E. Finkelstein, C. Feng, N. P. Restifo, and P. Hwu Dendritic Cells Strongly Boost the Antitumor Activity of Adoptively Transferred T Cells In vivo Cancer Res., September 15, 2004; 64(18): 6783 - 6790. [Abstract] [Full Text] [PDF]
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W. C. Bartholomae, F. H. Rininsland, J. C. Eisenberg, B. O. Boehm, P. V. Lehmann, and M. Tary-Lehmann T Cell Immunity Induced by Live, Necrotic, and Apoptotic Tumor Cells J. Immunol., July 15, 2004; 173(2): 1012 - 1022. [Abstract] [Full Text] [PDF]
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 M. Salio, M. J. Palmowski, A. Atzberger, I. F. Hermans, and V. Cerundolo CpG-matured Murine Plasmacytoid Dendritic Cells Are Capable of In Vivo Priming of Functional CD8 T Cell Responses to Endogenous but Not Exogenous Antigens J. Exp. Med., February 17, 2004; 199(4): 567 - 579. [Abstract] [Full Text] [PDF]
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L. A. O'Mara and P. M. Allen Pulmonary Tumors Inefficiently Prime Tumor-Specific T Cells J. Immunol., January 1, 2004; 172(1): 310 - 317. [Abstract] [Full Text] [PDF]
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I. F. Hermans, T. W. Chong, M. J. Palmowski, A. L. Harris, and V. Cerundolo Synergistic Effect of Metronomic Dosing of Cyclophosphamide Combined with Specific Antitumor Immunotherapy in a Murine Melanoma Model Cancer Res., December 1, 2003; 63(23): 8408 - 8413. [Abstract] [Full Text] [PDF]
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H. Tahara, K. Fujio, Y. Araki, K. Setoguchi, Y. Misaki, T. Kitamura, and K. Yamamoto Reconstitution of CD8+ T Cells by Retroviral Transfer of the TCR {alpha}{beta}-Chain Genes Isolated from a Clonally Expanded P815-Infiltrating Lymphocyte J. Immunol., August 15, 2003; 171(4): 2154 - 2160. [Abstract] [Full Text] [PDF]
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L. Krishnan, S. Sad, G. B. Patel, and G. D. Sprott Archaeosomes Induce Enhanced Cytotoxic T Lymphocyte Responses to Entrapped Soluble Protein in the Absence of Interleukin 12 and Protect against Tumor Challenge Cancer Res., May 15, 2003; 63(10): 2526 - 2534. [Abstract] [Full Text] [PDF]
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U. Blohm, E. Roth, K. Brommer, T. Dumrese, F. M. Rosenthal, and H. Pircher Lack of Effector Cell Function and Altered Tetramer Binding of Tumor-Infiltrating Lymphocytes J. Immunol., November 15, 2002; 169(10): 5522 - 5530. [Abstract] [Full Text] [PDF]
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R. Dudani, Y. Chapdelaine, H. v. Faassen, D. K. Smith, H. Shen, L. Krishnan, and S. Sad Multiple Mechanisms Compensate to Enhance Tumor-Protective CD8+ T Cell Response in the Long-Term Despite Poor CD8+ T Cell Priming Initially: Comparison Between an Acute Versus a Chronic Intracellular Bacterium Expressing a Model Antigen J. Immunol., June 1, 2002; 168(11): 5737 - 5745. [Abstract] [Full Text] [PDF]
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R. Ganss, E. Ryschich, E. Klar, B. Arnold, and G. J. Hammerling Combination of T-Cell Therapy and Trigger of Inflammation Induces Remodeling of the Vasculature and Tumor Eradication Cancer Res., March 1, 2002; 62(5): 1462 - 1470. [Abstract] [Full Text] [PDF]
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L. T. Nguyen, A. R. Elford, K. Murakami, K. M. Garza, S. P. Schoenberger, B. Odermatt, D. E. Speiser, and P. S. Ohashi Tumor Growth Enhances Cross-Presentation Leading to Limited T Cell Activation without Tolerance J. Exp. Med., February 11, 2002; 195(4): 423 - 435. [Abstract] [Full Text] [PDF]
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A. Perez-Diez, P. J. Spiess, N. P. Restifo, P. Matzinger, and F. M. Marincola Intensity of the Vaccine-Elicited Immune Response Determines Tumor Clearance J. Immunol., January 1, 2002; 168(1): 338 - 347. [Abstract] [Full Text] [PDF]
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H. N. Le, N. C. Lee, K. Tsung, and J. A. Norton Pre-Existing Tumor-Sensitized T Cells Are Essential for Eradication of Established Tumors by IL-12 and Cyclophosphamide Plus IL-12 J. Immunol., December 15, 2001; 167(12): 6765 - 6772. [Abstract] [Full Text] [PDF]
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S. Radoja, M. Saio, D. Schaer, M. Koneru, S. Vukmanovic, and A. B. Frey CD8+ Tumor-Infiltrating T Cells Are Deficient in Perforin-Mediated Cytolytic Activity Due to Defective Microtubule-Organizing Center Mobilization and Lytic Granule Exocytosis J. Immunol., November 1, 2001; 167(9): 5042 - 5051. [Abstract] [Full Text] [PDF]
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S. Radoja, M. Saio, and A. B. Frey CD8+ Tumor-Infiltrating Lymphocytes Are Primed for Fas-Mediated Activation-Induced Cell Death But Are Not Apoptotic In Situ J. Immunol., May 15, 2001; 166(10): 6074 - 6083. [Abstract] [Full Text] [PDF]
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N. Dalyot-Herman, O. F. Bathe, and T. R. Malek Reversal of CD8+ T Cell Ignorance and Induction of Anti-Tumor Immunity by Peptide-Pulsed APC J. Immunol., December 15, 2000; 165(12): 6731 - 6737. [Abstract] [Full Text] [PDF]
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P. Rawson, I. F. Hermans, S. P. Huck, J. M. Roberts, H. Pircher, and F. Ronchese Immunotherapy with Dendritic Cells and Tumor Major Histocompatibility Complex Class I-derived Peptides Requires a High Density of Antigen on Tumor Cells Cancer Res., August 1, 2000; 60(16): 4493 - 4498. [Abstract] [Full Text]
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 M. Oelke, U. Moehrle, J.-L. Chen, D. Behringer, V. Cerundolo, A. Lindemann, and A. Mackensen Generation and Purification of CD8+ Melan-A-specific Cytotoxic T Lymphocytes for Adoptive Transfer in Tumor Immunotherapy Clin. Cancer Res., May 1, 2000; 6(5): 1997 - 2005. [Abstract] [Full Text]
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A. Prevost-Blondel, E. Roth, F. M. Rosenthal, and H. Pircher Crucial Role of TNF-{alpha} in CD8 T Cell-Mediated Elimination of 3LL-A9 Lewis Lung Carcinoma Cells In Vivo J. Immunol., April 1, 2000; 164(7): 3645 - 3651. [Abstract] [Full Text] [PDF]
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S. Radoja, T. D. Rao, D. Hillman, and A. B. Frey Mice Bearing Late-Stage Tumors Have Normal Functional Systemic T Cell Responses In Vitro and In Vivo J. Immunol., March 1, 2000; 164(5): 2619 - 2628. [Abstract] [Full Text] [PDF]
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M. J. Dobrzanski, J. B. Reome, and R. W. Dutton Therapeutic Effects of Tumor-Reactive Type 1 and Type 2 CD8+ T Cell Subpopulations in Established Pulmonary Metastases J. Immunol., June 1, 1999; 162(11): 6671 - 6680. [Abstract] [Full Text] [PDF]
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A. F. Ochsenbein, P. Klenerman, U. Karrer, B. Ludewig, M. Pericin, H. Hengartner, and R. M. Zinkernagel Immune surveillance against a solid tumor fails because of immunological ignorance PNAS, March 2, 1999; 96(5): 2233 - 2238. [Abstract] [Full Text] [PDF]
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