Preferentially Expressed Antigen In Melanoma (PRAME)

PRAME is predominantly expressed in human melanomas and that is recognized by cytolytic T lymphocytes. It is not expressed in normal tissues, except testis. This expression pattern is similar to that of other CT antigens, such as MAGE, BAGE and GAGE. However, unlike these other CT antigens, this gene is also expressed in acute leukemias. The deduced 509-amino acid PRAME protein contains no signal sequence. Northern blot analysis detected 2.2- and 3.0-kb PRAME transcripts in tumor cell lines but not in normal tissue except testis. RT-PCR analysis detected very low expression of PRAME in ovary and adrenals. Functional analysis showed that PRAME-specific CTLs can lyse MEL.B but not MEL.A cells due to inhibition mediated by the interaction of a p58.2 molecule (KIR2DL2) on the CTLs with HLA-Cw7 on the melanoma target cell.