Hiding in plain sight: Misinterpretation of immunogenic DPB epitopes within G/P groups

Area of Science:

• Immunogenetics
• Transplantation Immunology

Background:

• Clinical impact of HLA-DP antibodies is not well understood, leading to varied strategies for transplant candidates and recipients.
• Current HLA-DPB naming conventions and typing methods (G/P codes) may obscure immunogenic epitopes.
• Differences outside Exon 2 of DPB were historically considered non-immunogenic.

Purpose of the Study:

• To investigate the immunogenicity of specific polymorphisms in HLA-DPB Exon 3.
• To highlight how current typing methods may lead to inaccurate compatibility assessments.
• To emphasize the clinical relevance of HLA-DPB antibodies in transplantation.

Main Methods:

• Case study analysis of four transplant scenarios.
• Review of HLA-DPB typing conventions and sequence alignments.
• Identification of polymorphisms at codons 96R/K and 170I/T in Exon 3.

Main Results:

• Polymorphisms at codons 96R/K and 170I/T in HLA-DPB Exon 3 were identified as targets for alloantibody recognition.
• These immunogenic regions are not adequately identified by current G/P code-level typing.
• Inaccurate compatibility assessments and misinterpreted antibody responses may occur.

Conclusions:

• HLA-DPB histocompatibility assessments are complex and require more detailed analysis beyond Exon 2.
• Current typing systems may fail to detect critical antibody targets, potentially leading to adverse transplant outcomes.
• Adaptable systems are needed to align with evolving research and improve transplant compatibility assessments.