Cancer Immune Therapy Edited by G. Stuhler and P. Walden ...

48 4 T Cells In Tumor Immunity
Although T cells directed against tumor antigens other than Melan-A are only rarely
found in the ex vivo TILs or TILNs preparations from melanoma lesions, a much wider
spectrum of antigen specificities is found in 2±3 weeks TIL and TILNs cultured in cytokines
as described above. As shown in Tab. 4.1, we identified T cells specific for at least
four different HLA-A2 tumor-associated antigens other than Melan-A in the same
TILN preparation from a melanoma patient. Interestingly, this patient has had an unusually
favorable clinical course and remains tumor-free 6 years after removal of this
metastatic lymph node. Similar analyses with HLA-A2/peptide tetramers of 2- to
3-week expanded TILs and TILNs reveal a similar trend. The existence of other tumor
antigen-specific T cells including melanocyte/melanoma differentiation antigens and
the so-called cancer/testis antigens. The latter include MAGE-A10, NY-ESO-1 and
CAMEL. These observations suggest that perhaps an important proportion of the CD8 +
T lymphocytes present in the TIL/TILN populations may in fact be tumor-specific.
Future studies with panels of tetramers representing a large group of tumor antigens
might allow us to catalogue the diversity of antigen-specific T cells in the same individual,
at individual tumor sites. Important steps in this direction have recently been
reported using panels of cDNAs and transfection approaches. In one study, the reactivity
of melanoma TIL populations was analyzed using COS cells co-transfected
with individual cDNAs coding for defined melanoma associated antigens and
cDNAs encoding HLA class I molecules. Five melanosomal proteins and five HLA-A
alleles were included in this analysis [70]. In the other study, this approach was extended
to the analysis of 28 cDNAs encoding already defined tumor antigens and 31
HLA class I alleles [72]. It was observed that indeed the spectrum of tumor antigens
recognized by a given TIL population can be large. For instance, 10 TIL populations
Tab. 4.1 The antitumor CTL response can target multiple antigens in the same individual at the
same tumor site
Tumor antigen Antigenic peptide sequence Percent lymphocytes Reference
tetramer + CD8 +a
Melan-A/MART-1 b
Tyrosinase b
NY-ESO- d
MAGE-A10 d
CAMEL d
SSX-2 d
1.8 71
YMDGTMSQV 0.02
SLLMWITQC 1.1 67
GLYDGMEHL 2.168
MLMAQEALAFL 0.22 96
KASEKIFYV 0.64 97
ELAGIGILTV c
a Fluorescently labeled tetramers of HLA-A2
and the corresponding antigenic peptides
listed on the first column to the left were used
together with anti-CD8±FITC to label a TILN
cell suspension from a cutaneous melanoma
patient, LAU 50. Labeled cells were analyzed
by flow cytometry and the results are reported
as percentage of tetramer + CD8 + among the
total CD8 + lymphocytes.
b Tetramer measurement was performed in the
freshly prepared lymph node cell suspension.
The levels of tyrosinase tetramer + T cells are
below the detection limit and their characterization
was not pursued further.
c This is a peptide analogue of the Melan-A/
MART-1immunodominant HLA-A2 restricted
peptide that has increased antigenicity and immunogenicity
as described elsewhere [98].
d Tetramer measurement was performed on the
TILN populations after two to three weeks in
culture in medium supplemented with human
serum, rIL-2 and rIL-7, as described [71].