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

Abstract

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 β₂‐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‐A*0102, A*6601, B*5801, B*5802, Cw*0302 and Cw*0602. 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: A*0102 and B*5802. The A*0102 allele differs from A*0101 by 5 nucleotide substitutions within exon 2 where it has a motif shared with A*30 alleles; the B*5802 allele differs from B*5801 by 3 substitutions in exon 3 where it has a motif shared with B*14 alleles. Subtyping HLA‐A 1 alleles showed A*0102 was well represented amongst individuals typed serologically as Al in an African population but was absent from caucasoids. B*5802 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.