| Research Abstract |
1. A cDNA clone encoding a new HLA class II antigen <alpha> chain, named DO<alpha>, was isolated from a human CDNA library using the DR<alpha>, DO<alpha> and DP<alpha> cDNA probes.
The nucleotide sequence of the DO<alpha> cDNA was distinct from those of the DR<alpha>, the DO<alpha>, and the DP<alpha> cDNA, but showed some characteristic features of the class II antigen <alpha>-chain. We also isolated and identified genomic clones specifying the DO<alpha> gene. Genomic Southern hybridization analyses of cell lines with different HLA-DR serotypes indicated the existence of a single DO<alpha> gene that exhibited little restriction enzyme polymorphism.
2. To describe the function of gene products from this new DO locus, DO gene clone was introduced. The resultant transfectant cells were analyzed their expression and function using biochemical and cellular-immunological procedure.
3. A genomic clone specifying a new HLA class II antigen <beta> chain pseudogene, named DV<beta>, was isolated from a human genomic phage library using a DO<beta> cDNA probe.
Southern hybridization and nucleotide sequence analyses identified the <beta>2 domain exon (exon 3) with several deleterious mutations and the CP-TM-CY exon (connecting peptide, transmembrane, and cytoplasmic exon, exon 4), but the first, second and fifth exons of normal <beta> chains were entirely missing. The nucleotide sequence of these two exons were distinct from those of other class II <beta>-chain genes, but slightly more related to the DQ<beta> and the DX<beta> genes than other class II genes. Cosmid clone analysis around the DV<beta> gene placed DV<beta> between DX<alpha> and DQ<beta>, 15 kb upstream from DX<alpha>, which was consistence with that around DX<alpha> which was hown by RFLP(restriction fragment length polymorphism studies).
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