HLA expression and tumor-infiltrating immune cells in uveal melanoma.
BACKGROUND
In uveal melanoma, both the amount of tumor-infiltrating cells and the level of expression of HLA antigens are quite variable. We hypothesized that low levels of HLA expression lead to a lack of antigen presentation, which might prevent proper immunologic recognition of the tumor. This lack of recognition might subsequently lead to low levels of tumor-infiltrating cells.


METHODS
To test this hypothesis, we determined the type and number of tumor-infiltrating cells in tumor sections from 24 uveal melanomas. We applied monoclonal antibodies directed against different types of immune cells and compared the results with the expression of HLA class I and class II antigens on the tumor cells.


RESULTS
Infiltrating immune cells were observed in all uveal melanomas (although in small amounts), with a predominance of T lymphocytes. Significant positive correlations were observed between the number of CD3+ cells (T lymphocytes) and monomorphic HLA class I expression, allele-specific HLA-A2 and Bw4 expression, and HLA class II expression. Furthermore, the number of CD4+ cells (T helper cells, monocytes/ macrophages) and of CD11b+ cells (monocytes/macrophages) was significantly correlated with the level of monomorphic HLA class I expression.


CONCLUSIONS
These data support our hypothesis that low levels of HLA expression (and therefore a lack of presentation of tumor-specific antigens) may lead to a low level of tumor infiltrate.
de Waard-Siebinga
I
I
Department of Ophthalmology, University Hospital Leiden, The Netherlands.
Hilders
C G
CG
Hansen
B E
BE
van Delft
J L
JL
Jager
M J
MJ
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000911:Antibodies, Monoclonal; D015703:Antigens, CD / Q000276:immunology; D005260:Female; D015395:Histocompatibility Antigens Class I / Q000276:immunology*; D000949:Histocompatibility Antigens Class II / Q000276:immunology*; D006801:Humans; D007124:Immunoenzyme Techniques; D007962:Leukocytes / Q000276:immunology; D016246:Lymphocytes, Tumor-Infiltrating / Q000276:immunology*; D008297:Male; D008545:Melanoma / Q000276:immunology*; D008875:Middle Aged; D014604:Uveal Neoplasms / Q000276:immunology*
D000911:Antibodies, Monoclonal; D015703:Antigens, CD; D015395:Histocompatibility Antigens Class I; D000949:Histocompatibility Antigens Class II