Characterization of HLA class I altered phenotypes in a panel of human melanoma cell lines
Rosa Méndez1, Teresa Rodríguez, Ana Del Campo
1Departamento de Análisis Clínicos, Hospital Universitario Virgen de las Nieves, Universidad de Granada, Avd. Fuerzas Armadas 2, 18014, Granada, Spain.
Background:
Altered HLA class I cell surface expression is one of the major mechanisms by which tumor cells escape from T lymphocytes. Immunohistochemistry-defined phenotypes of lost HLA class I expression have been described in human solid tumors, nut less information is available on melanoma cell lines.
Objectives:
To describe the frequency and distribution of different types of HLA class I antigen alterations in 91 melanoma cell lines from the European Searchable Tumour Cell and Databank (ESTDAB).
Methods:
The HLA class I expression was assessed by flow cytometry and HLA genotyping.
Results:
We found various types of HLA class I cell surface alterations in about 67% of the melanoma cell lines. These alterations range from total to selective HLA class I loss due to loss of heterozygosity (LOH), haplotype loss, beta2-microglobulin gene mutation, and/or total or selective down-regulation of HLA class I molecules. The most frequently observed phenotype is down-regulation of HLA-B locus that was reversible after treatment with IFN -gamma.
Conclusions:
In general, HLA class I alterations in the majority of the cells analyzed were of regulatory nature and could be restored by IFN-gamma. Analysis of the frequency of distinct HLA class I altered phenotypes in these melanoma cell lines revealed specific differences compared to other types of tumors.
