Fig. 1.

Distribution of HLA class I phenotypes in 91 human melanoma cell lines (ESTDAB) and in different solid tumours. These tumours include melanoma [19], bladder cancer [30], colorectal carcinoma [29], laryngeal [28] and cervical cancer [22]. The following HLA class I expression phenotypes are compared: total loss or downregulation of HLA class I (Phenotype I); haplotype loss (Phenotype II); locus downregulation (Phenotype III); allelic loss (Phenotype IV), compound phenotype (Phenotype V); resistance to stimulation with IFN-gamma (Phenotype VI). Surface expression of HLA class I molecules in ESTDAB melanoma cell lines was determined by flow cytometry (mean fluorescence intensity, MFI) using anti-HLA class I specific antibodies. To analyse induction with IFN-gamma the melanoma cells were treated with 800 U/ml for 48 h