The HLA-A,B,C genotype of the class I negative cell line Daudi reveals novel HLA-A and -B alleles.

Daudi, a lymphoblastoid B cell line derived from an African Burkitt lymphoma does not express HLA-A,B,C antigens at the cell surface. Although HLA-A,B,C heavy chains are made normally they do not assemble into functional molecules because beta 2-microglobulin is absent. Previous serological analysis of somatic cell hybrids indicated that the HLA haplotypes of Daudi encoded HLA-A1, A10(A26), B17, and B16(38) antigens. Here we describe the application of molecular methods: ARMS-PCR, cDNA cloning and sequencing, immunoprecipitation and gel electrophoresis, to define the class I genotype of the Daudi cell line which is HLA-A0102, A6601, B5801, B5802, Cw0302 and Cw0602. With the exception of the B38 antigen, which is not a product of the alleles defined, the genotype is consistent with the serological description. Two previously undiscovered alleles emerged from this analysis: A0102 and B5802. The A0102 allele differs from A0101 by 5 nucleotide substitutions within exon 2 where it has a motif shared with A30 alleles; the B5802 allele differs from B5801 by 3 substitutions in exon 3 where it has a motif shared with B14 alleles. Subtyping HLA-A1 alleles showed A0102 was well represented amongst individuals typed serologically as A1 in an African population but was absent from caucasoids. B5802 has been found in a second individual. Thus the novel A and B alleles are not specific to the Daudi tumor. Overall, this analysis of a single East African cell illustrates the power of molecular methods to define new class I HLA alleles in non-caucasoid populations.