HLA-E: A novel HLA class I gene expressed in resting T lymphocytes

A MHC class I gene, HLA-6.2, has been identified. Examination of its primary structure indicates that HLA-6.2 is the most divergent member of the class I gene family characterized to date. Tissue distribution of HLA-6.2 RNA differs from other class I genes in that the highest level of RNA is detected in resting T lymphocytes. After transfer of the HLA-6.2 gene into a class I null human lymphoblastoid cell line, a protein associated with β₂-microglobulin is detected. Analysis of HLA deletion mutant cell lines places the HLA-6.2 gene between the HLA-C and HLA-A loci on the short arm of chromosome 6. These data support the fact that the HLA-6.2 gene is a distinct expressible HLA class I gene, which we propose be designated HLA-E.