THE HLA-A,B,C GENOTYPE OF THE CLASS-I NEGATIVE CELL-LINE DAUDI REVEALS NOVEL HLA-A AND HLA-B ALLELES

Daudi, a lymphoblastoid B cell line derived from an African Burkitt ly mphoma does not express HLA-A,B,C antigens at the cell surface. Althou gh HLA-A,B,C heavy chains are made normally they do not assemble into functional molecules because Pz-microglobulin is absent. Previous sero logical analysis of somatic cell hybrids indicated that the HLA haplot ypes of Daudi encoded HLA-A1, A10(A26), B17, and B16(38) antigens. Her e we describe the application of molecular methods: ARMS-PCR, cDNA clo ning and sequencing, immunoprecipitation and gel electrophoresis, to d efine the class I genotype of the Daudi cell line which is HLA-A0102, A6601, B*5801, B*5802, Cw*0302 and Cw*0602. With the exception of th e B38 antigen, which is not a product of the alleles defined, the geno type is consistent with the serological description. Two previously un discovered alleles emerged from this analysis: A0102 and B*5802. The A0102 allele differs from A*0101 by 5 nucleotide substitutions within exon 2 where it has a motif shared with A30 alleles; the B*5802 alle le differs from B5801 by 3 substitutions in exon 3 where it has a mot if shared with B14 alleles. Subtyping HLA-A1 alleles showed A*0102 wa s well represented amongst individuals typed serologically as Al in an African population but was absent from caucasoids. B5802 has been fo und in a second individual. Thus the novel A and B alleles are not spe cific to the Daudi tumor. Overall, this analysis of a single East Afri can cell illustrates the power of molecular methods to define new clas s I HLA alleles in non-caucasoid populations.