| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
,§
*
Institute of Immunology and Infectious Diseases, University of Verona, Verona, Italy;
Servizio/Cattedra di Immunologia, Ospedale S. Martino, Universitá di Genova, Genoa, Italy;
Unit of Cellular and Molecular Genetics, Advanced Biotechnology Center, Genoa, Italy; and
§
Department of Clinical and Biological Sciences, University of Pavia, Varese, Italy
 |
Abstract |
|---|
 Top Abstract IntroductionMaterials and MethodsResultsDiscussionReferences |
|---|
-induced MHC class II gene
transcription. We show here that the MHC class II negative phenotype of
the human hepatocarcinoma cell lines Alexander and HepG2 remains
unmodified after treatment with IFN-, although MHC class I
expression is up-modulated. This correlates with absence of CIITA
mature transcripts. Transfection of an expressible CIITA cDNA in
Alexander cells resulted in a very high cell surface expression of all
three human class II subsets, HLA-DR, -DP and -DQ, indicating that
normally observed induction of CIITA expression by IFN- is probably
blocked, in the hepatocarcinoma cell lines, at the level of CIITA
transcription and not at the level of IFN- receptor binding and
signal transduction mechanisms. To assess whether MHC class II
expression on CIITA-transfected Alexander cells could have functional
relevance, we tested their capacity to present antigenic peptides to an
HLA-DR-restricted T cell line specific for a peptide of
Mycobacterium tuberculosis Ag85 protein. It was
found that the transfected cells could not only present the exogenously
supplemented peptide but also process Ag85 protein to generate the
specific epitope recognized by the HLA-DR-restricted T cell line.
Similar results were obtained with CIITA-transfected CFPAC-1 pancreatic
adenocarcinoma cells, which differed from Alexander cells in that they
were inducible by IFN-. These results suggest new strategies to act
on CIITA for increasing the potential of a tumor cell to present
putative tumor Ags to the immune system. |
Introduction |
|---|
|
TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
|---|
certainly
constitutes an important member (5, 6). Most regulation of expression of MHC class II molecules is under the control of transcriptional mechanisms that are both cell type and development specific (7, 8, 9). In this context, a pivotal role is played by the CIITA transcriptional activator (10) encoded by the AIR-1 locus (11). Defects impairing AIR-1 locus function result in failure to transcribe all class II gene subsets, as in the B cell mutant RJ2.2.5 (12), as well as in some B cell lines derived from patients affected by bare lymphocyte syndrome (4).
Expression of CIITA is also required for IFN--inducible MHC class II
expression, as demonstrated by the analysis of IFN--inducible normal
cells (13) and cell lines (14, 15, 16). Moreover, transfection of CIITA
cDNA under the control of a ubiquitous promoter in MHC class
II-inducible cells results in a constitutive class II expression (14, 16), confirming and extending previous observations on the dominance of
the constitutive class II-positive over the inducible phenotype in
somatic cell hybrids (17, 18). Interestingly, terminal differentiation
of B cells in plasma cells is accompanied by loss of MHC class II gene
expression. This event is mediated by dominant suppressor factors
activated and/or expressed in plasma cells that suppress the MHC class
II gene transcription (19, 20). It has been recently shown that the
developmental extinction of class II expression in plasma cells is
accompanied by the lack of expression of the AIR-1 gene
product, as assessed by the absence of CIITA mRNA in human and mouse
plasmacytoma cell lines, as well as in (B cell x plasma cell)
class II-negative somatic cell hybrids. Stable transfection of a
constitutively expressible CIITA cDNA under the control of a ubiquitous
promoter restored expression of human class II genes in both the
plasmacytoma cell model (21), and in the (B cell x plasma cell)
somatic cell hybrids (22), demonstrating that the AIR-1
locus is indeed the real target of the active suppression that results
in the loss of class II gene expression in plasma cells.
Taken together, these observations demonstrate that the AIR-1 gene-encoded CIITA is a major physiologic regulator of the expression of MHC class II genes.
Tumor cells derived from nonlymphoid tissues sometimes express de novo
MHC class II genes or are induced to do so by stimulation with IFN-.
Although the genetic mechanisms underlying these events are still
elusive, it has been shown that in certain tumors de novo expression of
MHC class II genes can result in enhanced elimination of the cancer
cell by the immune system. It is believed that in these cases tumor
cells can serve as APCs for tumor-associated Ags and thus facilitate
tumor rejection (23, 24).
Hepatocarcinomas, as their normal cell counterpart (25), do not express
class II genes, with few exceptions (26, 27). Moreover, although in
some circumstances normal human hepatocytes can be induced to express
class II genes both in vivo, as in hepatitis B virus (HBV) infection
and in active cirrhosis (28, 29), and in vitro, by IFN- (28), most
hepatocarcinoma tumors are refractory to induction (26), behaving as
constitutive MHC class II-negative cells. The hepatocarcinoma cell
lines Alexander and HepG2 are included in this group. We therefore
decided to analyze the pattern of expression of CIITA in Alexander and
HepG2 and founded that it was not expressed in both cell lines. We then
explored the genetic and immunologic effects of stable transfection of
an expressible CIITA cDNA and particularly the effects on MHC class II
gene expression and the possible functional relevance of this
expression.
|
Materials and Methods |
|---|
|
TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
|---|
Alexander and HepG2 are human hepatocarcinoma cell lines (26, 28). CFPAC-1 is a cell line derived from human pancreatic adenocarcinoma (6). Raji is an MHC class II-positive human B cell lymphoma. They were propagated in RPMI 1640 medium supplemented with 10% FCS and glutamine. Parental cells and transfectants (see below) were analyzed by indirect immunofluorescence and cytofluorometry on an Epics Profile apparatus (Coulter, Hialeah, FL), with a series of mAbs specific for the various subsets of human MHC class II Ags. Relevant to this work were the following reagents: D1–12, specific for human DR Ags; B7/21, specific for human DP Ags; BT 3/4, XIII 358.4 and XIV 466.2, specific for DQ1, DQ2, and DQ3 molecules, respectively, and recognizing the distinct DQ heterodimers present in Raji (DQ1/DQ2), and the possible products of the alleles present in Alexander (DQ1), HepG2 (DQ1/DQ3), and CFPAC-1 (DQ1) cells.
IFN- treatment
Cells were incubated in the presence of recombinant human
IFN-, kindly donated by Dr. V. Cantone, Roussel Pharma, Milan,
Italy. The concentration of 1000 U/ml in RPMI 1640 medium supplemented
with 10% FCS was used. After 72 h incubation, cells were washed
and analyzed for the expression of cell surface Ags by cytofluorometric
techniques. The dose of IFN- and the incubation time were chosen on
the basis of preliminary experiments showing maximum induction of HLA
Ags in control cell lines including the pancreatic adenocarcinoma
CFPAC-1 (6).
Generation of stable transfectants expressing exogenous CIITA
The full-length human CIITA cDNA (10), kindly donated by Dr. B. Mach (Geneva, Switzerland), was subcloned into the eukaryotic expression vector pREP-10, containing the hygromycin B resistance gene (Invitrogen, San Diego, CA). The resulting construct, designated pREP-10/CIITA, linearized by ClaI restriction enzyme digestion, was stably introduced into Alexander and CFPAC-1 cell lines by liposome-mediated transfection using the Transfection Reagent kit (DOTAP, Boehringer Mannheim Italia, Milan, Italy). To isolate stable transfectants, selection for hygromycin resistance was applied after 24 to 48 h, using 250 µg/ml of hygromycin.
DNA and RNA analysis
Genomic DNA was analyzed by Southern blotting after digestion with BamHI restriction endonuclease. The CIITA probe used was a 5'-end 3-kb BamHI fragment from the full length CIITA cDNA. The presence of CIITA cytoplasmic RNA, as well as In chain, DMA- and DMB-specific transcripts, was assessed by RT-PCR using the Perkin-Elmer GeneAmp RNA PCR kit (Perkin-Elmer Italia, Monza, Italy), according to the manufacturer’s recommendations. Primers specific for CIITA, ß-actin, In chain, and DMB mRNA and RT-PCR conditions were as described by Chang et al. (16, 30). Primers specific for DMA were as follows: sense 5'-GTGCAAGTAGCCAAAACCA-3', antisense 5'TACCACACAGGTGTAAGTGT-3'.
Ag processing and presentation to T cells
Alexander cells, CFPAC-1 cells, and their corresponding CIITA transfectants were detached with trypsin-EDTA, irradiated at 6000 rad with a 137Cs source (Gammacell, Nordion, Inc., Kanata, Canada) and dispensed at different concentrations in a flat-bottom microtiter plate. PBMC from two individuals, each sharing the same HLA-DR alleles with Alexander and CFPAC-1 cells, respectively, were used as positive controls for Ag presentation to T cells. PBMC were irradiated at 3000 rad and dispensed in microtiter plate. After overnight incubation, wells containing PBMC were gently washed with prewarmed medium to remove nonadherent cells. Both adherent monocytes (AM) and malignant cells were pulsed with 5 µg/ml of purified protein derivative (PPD)3 (Statens Seruminstitute, Copenhagen, Denmark), 5 µg/ml Ag85, a highly purified mycobacterial secretory protein (31), or with 1 µg/ml of a peptide of Ag85, designated pep11 (aa 91–108, GCQTYKWETLLTSELPQW), for 4 h. CD4+ T cells (2 x 104 from an established line specific for pep11 and restricted by the HLA-DR*15 allele) were then added in 100 L medium to the wells, as described (32, 33). After 2 days, the cultures were pulsed with 0.5 Ci [3H]thymidine (5 Ci/mmol specific activity, Amersham, Buckinghamshire, U.K.) and then harvested 12 h later with a Filtermate 196 apparatus. The dried filters were counted in a Matrix 96 counter (Packard Instrument, Downers Grove, IL). Results are given as kcpm (cpm x 103).
|
Results |
|---|
|
TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
|---|
treatment does not rescue HLA class II Ag expression in two
human class II-negative hepatocarcinoma cell lines
The human hepatocarcinoma cell lines Alexander and HepG2 were
analyzed for MHC class II surface expression by indirect
immunofluorescence and FACS analysis, before and after treatment with
IFN-. Table I
shows the mean values of
fluorescence obtained for class II HLA-DR, -DP, and -DQ and class I
HLA-A, -B, and -C Ag expression in Alexander and HepG2 hepatocarcinoma
cells, compared with the CFPAC-1 human pancreas adenocarcinoma cell
line. See Figure 2 below for the HLA class II histogram profiles of
Alexander and CFPAC-1 cells. IFN- treatment did not result in
appreciable HLA class II induction in both Alexander and HepG2 cell
lines, as compared with the significant induction of expression in the
CFPAC-1 cell line. On the other hand, treatment with the cytokine
resulted in substantial increase of HLA class I Ag expression both in
Alexander cells (twofold) and in HepG2 cells (fourfold) (see Table I).
These data indicate that lack of MHC class II induction in the two
hepatocarcinoma cell lines is not due to an intrinsic defect at the
level of the IFN- receptor binding or of signal transduction
pathways.
|
|
We investigated whether lack of MHC class II cell surface Ags in
hepatocarcinoma cell lines could correlate with the absence of specific
mature transcripts for the various class II genes. Indeed, analysis of
cytoplasmic mRNA demonstrated the absence of specific messages for all
the class II subsets (data not shown). We then analyzed whether lack of
class II gene transcription correlated with absence of expression of
the AIR-1 gene product CIITA. Figure 1 shows the results of RT-PCR performed
on cytoplasmic RNA of Alexander cells, either untreated
(Alex lane) or after treatment with IFN-
(Alex/IFN- lane). It can be seen that, in
both conditions, no CIITA-specific mRNA was detected in Alexander
cells. Similar results were obtained in HepG2 cells (data not shown).
As expected, CIITA-specific transcripts were instead expressed in the
CFPAC-1 pancreatic adenocarcinoma cells after treatment with IFN-
(lane CFPAC-1/IFN-) but not in untreated
cells.
|
-inducible
CFPAC-1 cells or to that of the constitutive CIITA-expressing Raji
cells. Under the above experimental conditions, the probe hybridized
with two major fragments of human genomic DNA of about 15 and 9 kb,
respectively, and a minor band of 5.6 kb (data not shown). De novo expression of class II, In chain and DMB genes and up-regulation of DMA gene in Alexander cells transfected with an expressible CIITA cDNA
Introduction of a CIITA cDNA clone under the control of a
ubiquitous promoter in Alexander cells generated transfectants
expressing CIITA-specific transcripts. The CIITA expression pattern of
a representative transfectant is shown in Figure 1
(Alex/CIITA lane) as compared with a similarly
raised CIITA transfectant of CFPAC-1 pancreatic adenocarcinoma cells.
In this latter case, no difference was observed between IFN--induced
and CIITA-transfected cells in the amounts of CIITA-specific
transcripts. As shown in Figure 2, both
CIITA-transfected cell lines, Alexander and CFPAC-1, expressed de novo
at the cell surface all three class II subsets HLA-DR, -DP, and -DQ, at
levels comparable with the MHC class II-positive human B cell
Raji.
The expression status of In chain, DMA and DMB genes whose products are
associated to class II molecules during distinct phases of class II
intracellular transport and whose expression may be influenced by CIITA
were also analyzed (see Fig. 1). Alexander hepatocarcinoma cells did
not express appreciable amounts of either In chain or DMB mRNA, whereas
they expressed low amounts of DMA transcripts. This pattern was
unchanged after IFN- treatment. On the other hand, uninduced CFPAC-1
cells expressed substantial amounts of In chain and DMA transcripts and
low but appreciable amounts of DMB mRNA. After IFN- treatment, In
chain, but not DMA or DMB, specific mRNA was increased. Transfection of
CIITA in Alexander cells resulted in a de novo expression of high
amounts of In and DMB mRNAs and in substantial increase in the
DMA-specific transcripts. Transfection of CIITA in CFPAC-1 cells
resulted in In chain mRNA increase comparable with that obtained after
IFN- treatment, in further increase of DMA-specific mRNA, and in a
strong increase of DMB transcripts, especially when compared with the
CIITA-constitutive Raji B cell line.
These results demonstrate that the lack of MHC class II gene expression
in human hepatocarcinoma cell Alexander, both in unstimulated and
IFN--stimulated conditions, is due to the impossibility to
transcribe the AIR-1 gene and by consequence to express the
corresponding CIITA trans-activator. They also demonstrate
that although In chain, DMB, and, to a lesser extent, DMA genes can be
up up-regulated by CIITA, their expression is not necessarily dependent
on the presence of the trans-activator as shown in CFPAC-1
cells.
Ag processing and presentation capacity of CIITA transfectants
To assess whether de novo expression of MHC class II genes on CIITA-transfected cells had functional relevance, we tested their capacity to present mycobacterial Ags to DR-restricted PPD-specific CD4+ T cell lines. These lines both respond to a specific epitope included in a peptide (pep11) spanning the region between aa 91 to 108 of Ag85. The first T cell line is restricted by the HLA-DR*15 allele (present in Alexander cells); the second cell line is restricted by the HLA-DR*11 allele (present in CFPAC-1 cells).
As shown in Figure 3, the MHC class
II-positive CIITA-transfected Alexander cells pulsed with pep11
(ALEX-CIITA, Fig. 3A) stimulated the pep11-specific T
cell line, indicating Ag-presenting competence. This ability was
dependent on the newly acquired MHC class II expression since the T
cell line did not proliferate in response to the untransfected, MHC
class II-negative Alexander cells pulsed with pep11 (ALEX, Fig. 3A). In addition, T cells were stimulated by whole
PPD (ALEX-CIITA, Fig. 3B) to a similar extent as by
pep11, suggesting also an Ag-processing function of the
CIITA-transfected cells. However, since PPD is a poorly defined mixture
of mycobacterial Ags, it may include degraded antigenic fragments that
could be presented by the restriction element independently of
processing. To confirm the Ag-processing capacity of CIITA-transfected
Alexander cells, we performed additional experiments by using the
protein Ag Ag85, a 30- to 32-kDa mycobacterial protein purified over
ion-exchange and gel filtration columns to exclude contamination by low
m.w. fragments (31). Figure 3 shows that, also in this case
(ALEX-CIITA, Fig. 3C), pep11-specific T cells can
proliferate to similar extent as when pep11 or PPD were used.
|
, D, E and F). Both the
exogenously provided peptide (Fig. 3D) and the whole
purified protein (Fig. 3F) were able to stimulate the
proliferation of the T cell line although to lesser extent as compared
with CIITA-transfected Alexander cells, indicating also in this case
acquisition of Ag-processing and presentation competence. It must be
stressed that the CFPAC-1 cells used in this experiments displayed a
class II-positive phenotype in only 70% of the population. It must be noted that the Ag-processing and presentation capacity of CIITA-transfected Alexander and CFPAC-1 cells resulted, at plateau, in a reduced efficiency of T cell stimulation when compared with professional APCs.
|
Discussion |
|---|
|
TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
|---|
As far as the first point is concerned, the results presented in this
work clearly demonstrate that two distinct human hepatocarcinoma cell
lines, Alexander and HepG2, do not express human class II genes because
they do not express the class II trans-acting activator
CIITA encoded by the AIR-1 locus. Moreover, stimulation with
IFN-, the most potent inducer of MHC class II gene expression
through the activation of CIITA expression, as shown previously (13, 14, 16) and confirmed here on the pancreatic adenocarcinoma cell line
CFPAC-1, was unable to rescue class II gene expression in the
hepatocarcinoma cell lines. Again, this correlated with inability to
express CIITA. This event was not due to defects in IFN- receptor
binding and/or cytoplasmic signal transduction pathways, since the
treatment with the cytokine could substantially increase the expression
of other cell surface molecules such as MHC class I molecules. Thus, it
is likely that, in the hepatocarcinoma cells analyzed in this study,
the impossibility to express CIITA and, by consequence, MHC class II
genes is related to either a developmental block or to a tumor-induced
defect affecting specifically the expression of the CIITA-encoding
AIR-1 gene.
Whatever the mechanism, it must affect the transcription of the
AIR-1 gene. Indeed, transfection of Alexander cells with a
CIITA-specific cDNA under the control of a ubiquitously expressible
promoter, resulted in expression of CIITA mRNA and in de novo
expression of MHC class II genes and corresponding molecules at high
levels. It will be therefore very important to pursue the analysis of
the molecular mechanisms regulating the expression of the
AIR-1 gene, the structure of the AIR-1 gene
promoter region (34, 35), its accessibility to specific transcription
factors and the mode of action in various cell types, and particularly
in tumor cells. Indeed, recent findings have strongly suggested that
two promoter sequences seem to control the constitutive
AIR-1 gene expression in B cells and dendritic cells whereas
a distinct promoter sequence is involved in the IFN--induced
expression (34).
The fact that, upon CIITA transfection, MHC class II genes are strongly expressed further reinforces the notion that neither the chromatin accessibility nor the function of the transcription factors required for a correct expression of class II genes is defective in the hepatocarcinoma cells.
Recently it has been demonstrated that, besides the peculiar function
as main switch for the expression of MHC class II genes, in several
cellular systems CIITA trans-activator may induce or
up-regulate other genes such as HLA-DMA, HLA-DMB, and Invariant chain
(30, 36). Interestingly, all these gene products are strongly involved
in Ag processing and presentation to T cells. Thus, classical
professional APCs, such as B cells and macrophages, may be strongly
dependent on expression of CIITA to exert their function. The
hepatocarcinoma cells analyzed in this study did not express CIITA;
thus they could not express MHC class II. In addition, the
hepatocarcinoma cell line Alexander did not express In chain and DMB
genes and expressed very low amounts of DMA transcripts. This
expression pattern was not modified by treatment with IFN-, but it
was drastically changed by CIITA transfection. Indeed, both In chain
and DMB genes were strongly induced, and DMA expression was
up-regulated. However, expression of CIITA was not necessary to induce
the expression of either In chain or DM genes. In fact, as demonstrated
by the present study, a CIITA-negative but IFN--inducible tumor cell
line of pancreatic origin, CFPAC-1, constitutively expressed
substantial amounts not only of In chain but also of DMA and DMB
transcripts, although transfection of CIITA could further increase the
expression of all the three genes.
Taken together, these results give further support to the notion that CIITA is involved in the coregulation of a variety of genes whose products are important for a correct Ag presentation function. Nevertheless they also establish that the role played by CIITA in the regulatory mechanism of In chain and DM gene expression is certainly distinct and less fundamental than the one played in the regulation of MHC class II gene expression. Therefore, if MHC class II gene expression in tumor cells is required to present putative tumor-associated Ags to T cells and trigger antitumor immune responses (23, 24), suppression of CIITA could be an important mechanism for neoplastic cells to escape immune control.
Based on the above considerations, we therefore asked whether
CIITA-transfected MHC class II-positive tumor cells could acquire
immunologic competence. The results presented in this study clearly
demonstrate that CIITA-mediated de novo expression of MHC class II
genes and corresponding proteins in both an IFN--uninducible and an
IFN--inducible tumor cell line is sufficient to impart Ag
presentation capacity to DR-restricted, PPD peptide-specific T cell
lines, not only when tumor cells are pulsed with the relevant peptide
but also when they are pulsed with native protein. Thus,
CIITA-transfected Alexander hepatocarcinoma and CFPAC-1 pancreatic
adenocarcinoma cells can perform both Ag processing and presentation
functions in absence of IFN- induction.
This result is at variance with a recently published observation
indicating that CIITA-mediated expression of class II genes in a class
II-negative, but IFN--inducible, melanoma cell line is sufficient to
impart peptide Ag presentation but not native protein Ag-processing
capacity (37). Interestingly, in the above report, treatment with
IFN- of both CIITA-transfected and untransfected melanoma cells
resulted in Ag presentation capacity when either the peptide or the
native protein Ag were used, suggesting that in this tumor model
activation of Ag-specific T cells requires additional CIITA-independent
factors inducible by IFN-. The reasons for the discrepancy between
these results and our results are not known, but they may be due to the
different cellular systems utilized in the two approaches. In fact,
that CIITA alone can be sufficient to impart Ag presentation capacity
was also recently reported by Armstrong and collaborators (38), who
have transduced MHC class II-negative murine sarcoma cells with the
trans-activator and shown that tumor cells express class II
molecules and can process exogenous intact lysozyme and present
peptides to Ag-specific T cell hybridomas. Distinct specialized
mechanisms for Ag uptake are exhibited by different APCs. Non
professional APCs probably perform Ag uptake through surface molecules
other than the canonical ones described for professional APCs. These
molecules can possibly vary among cell types and influence the Ag
processing pathways, with different requirements of proteolytic enzymes
and other factors (39).
CIITA-transfected Alexander and CFPAC-1 cells express high amounts of all assessable HLA class II subsets, including DR, DP and DQ, since the cell surface concentration of these molecules is at least equal to, if not higher than, the one present in professional APCs. However, their T cell stimulation capacity was four- to fivefold lower than the one of peripheral blood adherent cells. This could not be attributed to suboptimal Ag concentration because both peptide and native Ag were used in high excess and specific T cell lines were equally stimulated by tumor cells pulsed either with peptide or with the native protein Ag. Moreover they could not be attributed to deficient expression of In chain or DM genes, whose products are important for the intracellular trafficking and the peptide loading function of class II molecules, respectively, since In chain and DM genes were highly expressed in the CIITA-transfected tumor cells. Thus it is likely that the transfected tumor cells were indeed at their maximum potential of Ag processing and presentation.
Optimal activation of T cells in response to Ags requires at least two signals from APC: the Ag-specific signal delivered by peptide/MHC class II complex and a second signal delivered by costimulatory molecules, such as B7-1 or B7-2, interacting with their specific receptors on T cells, CD28 and CTLA-4 (40). Furthermore, the T cell activation is greatly facilitated by accessory molecule interactions between the APC and the T cells such as ICAM-1/LFA-3 (41). Untransfected and CIITA-transfected Alexander and CFPAC-1 cells are negative for B7-1, B7-2, and ICAM-1 costimulatory molecules. This may partially explain their reduced presenting capacity with respect to professional APC.
In conclusion, the results presented in this report establish for the
first time that the constitutive (IFN- noninducible) MHC class
II-negative phenotype, such as the one displayed by most
hepatocarcinoma cell lines, is due to lack of expression of the CIITA
trans-activator. This tumor model system can therefore be an
interesting tool to study the regulation of expression of the
CIITA-encoding AIR-1 gene. Moreover, expression of CIITA
after transfection reverts the class II-negative in a class II-positive
phenotype in the hepatocarcinoma cell line Alexander. The newly
acquired phenotype is sufficient to impart Ag processing and
presentation capacity to the tumor cells. Furthermore, this functional
property was present also in CIITA-transfected CFPAC-1 pancreatic
adenocarcinoma cells, which, at variance with Alexander cells, can
express class II genes after IFN- treatment. These results may allow
us to hypothesize the use of CIITA as a potent, physiologic, and
specific factor to increase the potential of tumor cell to be
recognized by the immune system (38), or, alternatively, as target gene
product to be down-modulated in those disease states characterized by
excessive and unwanted Ag presentation to the immune system, as in some
autoimmune diseases.
|
Acknowledgments |
|---|
|
Footnotes |
|---|
2 Address correspondence and reprint requests to Dr. Roberto S. Accolla, Unit of Cellular and Molecular Genetics, Advanced Biotechnology Center, Largo Rosanna Benzi, 10–16136 Genoa, Italy. E-mail address:
3 Abbreviations used in this paper: PPD, purified protein derivative; In, invariant.
Received for publication September 2, 1997. Accepted for publication March 20, 1998.
|
References |
|---|
|
TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
|---|
. J. Immunol. 156:4254.[Abstract]
mediated by the transactivator gene CIITA. Science 265:106. mutants reveals that defects in CIITA or RFX result in defective class II MHC and Ii gene induction. Immunity 1:687.[Medline]
induction of class I and class II major histocompatibility antigens in human hepatoma cell lines. P. Thiollais, ed. Viral Hepatitis and Liver Disease A. R. Liss, Inc, New York, N.Y. p. 217.
. J. Exp. Med. 182:1793.This article has been cited by other articles:
|
|
 |
|
  A. Alisa, S. Boswell, A. A. Pathan, L. Ayaru, R. Williams, and S. Behboudi Human CD4+ T Cells Recognize an Epitope within {alpha}-Fetoprotein Sequence and Develop into TGF-{beta}-Producing CD4+ T Cells J. Immunol., April 1, 2008; 180(7): 5109 - 5117. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 L. Mortara, P. Castellani, R. Meazza, G. Tosi, A. De Lerma Barbaro, F. A. Procopio, A. Comes, L. Zardi, S. Ferrini, and R. S. Accolla CIITA-Induced MHC Class II Expression in Mammary Adenocarcinoma Leads to a Th1 Polarization of the Tumor Microenvironment, Tumor Rejection, and Specific Antitumor Memory. Clin. Cancer Res., June 1, 2006; 12(11): 3435 - 3443. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
O. Stuve, S. Youssef, A. J. Slavin, C. L. King, J. C. Patarroyo, D. L. Hirschberg, W. J. Brickey, J. M. Soos, J. F. Piskurich, H. A. Chapman, et al. The Role of the MHC Class II Transactivator in Class II Expression and Antigen Presentation by Astrocytes and in Susceptibility to Central Nervous System Autoimmune Disease J. Immunol., December 15, 2002; 169(12): 6720 - 6732. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
W. J. Magner, A. L. Kazim, C. Stewart, M. A. Romano, G. Catalano, C. Grande, N. Keiser, F. Santaniello, and T. B. Tomasi Activation of MHC Class I, II, and CD40 Gene Expression by Histone Deacetylase Inhibitors J. Immunol., December 15, 2000; 165(12): 7017 - 7024. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 J. A. Harton and J. P.-Y. Ting Class II Transactivator: Mastering the Art of Major Histocompatibility Complex Expression Mol. Cell. Biol., September 1, 2000; 20(17): 6185 - 6194. [Full Text]
|
|
|
|
 |
|
 R. Chiari, G. Hames, V. Stroobant, C. Texier, B. Maillère, T. Boon, and P. G. Coulie Identification of a Tumor-specific Shared Antigen Derived From an Eph Receptor and Presented to CD4 T Cells on HLA Class II Molecules Cancer Res., September 1, 2000; 60(17): 4855 - 4863. [Abstract] [Full Text]
|
|
|
|
|
|
C. Lawson, A. M. McCormack, D. Moyes, S. Yun, J. W. Fabre, M. Yacoub, and M. L. Rose An Epithelial Cell Line That Can Stimulate Alloproliferation of Resting CD4+ T Cells, But Not After IFN-{gamma} Stimulation J. Immunol., July 15, 2000; 165(2): 734 - 742. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
B. K. Martin, J. G. Frelinger, and J. P.-Y. Ting Combination Gene Therapy with CD86 and the MHC Class II Transactivator in the Control of Lung Tumor Growth J. Immunol., June 1, 1999; 162(11): 6663 - 6670. [Abstract] [Full Text] [PDF]
|
|
| |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
