HLA-B*1303: a new example of poor correlation between serology and structure

Area of Science:

• Immunogenetics
• Molecular biology
• Serology

Background:

• The Human Leukocyte Antigen-B (HLA-B) locus exhibits greater allelic diversity and serologic complexity compared to the HLA-A locus.
• Understanding HLA allele variations is crucial for transplantation and disease association studies.

Purpose of the Study:

• To characterize the molecular structure and serologic details of a novel HLA-B allele, designated B*1303.
• To investigate the relationship between the molecular structure and serologic definition of HLA-B alleles.

Main Methods:

• Molecular analysis to determine nucleotide and amino acid sequences of the novel HLA-B allele.
• Serologic analysis to define the B*1303 allele's serologic group and associated epitopes.
• Comparative sequence analysis against known HLA-B alleles.

Main Results:

• B*1303 was serologically defined as a B21 Bw4-associated molecule.
• Molecularly, B*1303 is closely related to B13 alleles, differing by only three nucleotide and two amino acid substitutions from B*1302.
• Significant amino acid substitutions were observed when compared to B*4901, B*5001, and B*4005 alleles.
• Serologic analysis indicated the critical role of leucine 145 in the B13-specific epitope and glutamic acid 163 in B21 and B15, B57 epitopes.

Conclusions:

• B*1303 represents a new instance where serologic classification may not accurately reflect the structural relationships among HLA-B alleles.
• The study underscores the importance of molecular data in precisely defining HLA allele structures and relationships.
• Specific amino acid residues (Leu145, Glu163) are implicated in defining key HLA-B epitopes.