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

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5 Major Histocompatibility Complex Modulation and Loss
5.9.1
HLA-G Expression in Tumor Cells of Distinct Origin
Until now, there is limiting information available about HLA-G expression in human
tumors. HLA-G expression has been investigated both at the mRNA and protein levels
in a variety of tumor cell lines and surgically removed malignant lesions, especially
in melanoma [43]. Both antisera and mAb have been utilized in immunohistochemical
binding and immunochemical assays. Figure 5.20 shows a representative
example of a flow cytometric staining of untreated and IFN-g-treated RCC cells, but
not of autologous renal epithelial cells utilizing the anti-HLA-G mAb MEM [30].
Results in the literature about the frequency of HLA-G expression by malignant cells
are conflicting [132±137] (Tab. 5.5). High levels of HLA-G transcripts and/or proteins
are found in tumor biopsies and cell lines derived from melanoma when compared
to healthy skin or lymph nodes of the same patient [133]. In lung cancer, HLA-G ex-
Fig. 5.20 Differential HLA-G expression by RCC
cells and by normal renal epithelial cells. The untreated
and IFN-g-treated RCC cell lines
LE8915RC and MZ2733RCC as well as the cell
line MZ2733NN derived from a normal renal
epithelium were subjected to flow cytometric
analysis using the anti-HLA-G-specific mAb
MEM-G9 and a murine isotypic control antibody.
The choriocarcinoma cell line JEG-3 served as a
positive control. Results are expressed as histograms
demonstrating constitutive and IFN-gmediated
HLA-G expression in the cell lines
JEG3, LE89.15RCC and MZ2733RCC, but not in
the normal kidney cell line MZ2733NN.